refactor: remove OpError, use ErrBox everywhere (#7187)

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

46 files changed, 783 insertions, 1068 deletions

diff --git a/cli/errors.rs b/cli/errors.rs
new file mode 100644
index 000000000..6b53ac8d0
--- /dev/null
+++ b/cli/errors.rs
@@ -0,0 +1,236 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+//! There are many types of errors in Deno:
+//! - ErrBox: a generic boxed object. This is the super type of all
+//!   errors handled in Rust.
+//! - JSError: a container for the error message and stack trace for exceptions
+//!   thrown in JavaScript code. We use this to pretty-print stack traces.
+//! - Diagnostic: these are errors that originate in TypeScript's compiler.
+//!   They're similar to JSError, in that they have line numbers.
+//!   But Diagnostics are compile-time type errors, whereas JSErrors are runtime
+//!   exceptions.
+
+use crate::import_map::ImportMapError;
+use crate::swc_util::SwcDiagnosticBuffer;
+use deno_core::ErrBox;
+use deno_core::ModuleResolutionError;
+use rustyline::error::ReadlineError;
+use std::env;
+use std::error::Error;
+use std::io;
+
+fn get_dlopen_error_class(error: &dlopen::Error) -> &'static str {
+  use dlopen::Error::*;
+  match error {
+    NullCharacter(_) => "InvalidData",
+    OpeningLibraryError(ref e) => get_io_error_class(e),
+    SymbolGettingError(ref e) => get_io_error_class(e),
+    AddrNotMatchingDll(ref e) => get_io_error_class(e),
+    NullSymbol => "NotFound",
+  }
+}
+
+fn get_env_var_error_class(error: &env::VarError) -> &'static str {
+  use env::VarError::*;
+  match error {
+    NotPresent => "NotFound",
+    NotUnicode(..) => "InvalidData",
+  }
+}
+
+fn get_import_map_error_class(_: &ImportMapError) -> &'static str {
+  "URIError"
+}
+
+fn get_io_error_class(error: &io::Error) -> &'static str {
+  use io::ErrorKind::*;
+  match error.kind() {
+    NotFound => "NotFound",
+    PermissionDenied => "PermissionDenied",
+    ConnectionRefused => "ConnectionRefused",
+    ConnectionReset => "ConnectionReset",
+    ConnectionAborted => "ConnectionAborted",
+    NotConnected => "NotConnected",
+    AddrInUse => "AddrInUse",
+    AddrNotAvailable => "AddrNotAvailable",
+    BrokenPipe => "BrokenPipe",
+    AlreadyExists => "AlreadyExists",
+    InvalidInput => "TypeError",
+    InvalidData => "InvalidData",
+    TimedOut => "TimedOut",
+    Interrupted => "Interrupted",
+    WriteZero => "WriteZero",
+    UnexpectedEof => "UnexpectedEof",
+    Other => "Error",
+    WouldBlock => unreachable!(),
+    // Non-exhaustive enum - might add new variants
+    // in the future
+    _ => unreachable!(),
+  }
+}
+
+fn get_module_resolution_error_class(
+  _: &ModuleResolutionError,
+) -> &'static str {
+  "URIError"
+}
+
+fn get_notify_error_class(error: &notify::Error) -> &'static str {
+  use notify::ErrorKind::*;
+  match error.kind {
+    Generic(_) => "Error",
+    Io(ref e) => get_io_error_class(e),
+    PathNotFound => "NotFound",
+    WatchNotFound => "NotFound",
+    InvalidConfig(_) => "InvalidData",
+  }
+}
+
+fn get_readline_error_class(error: &ReadlineError) -> &'static str {
+  use ReadlineError::*;
+  match error {
+    Io(err) => get_io_error_class(err),
+    Eof => "UnexpectedEof",
+    Interrupted => "Interrupted",
+    #[cfg(unix)]
+    Errno(err) => get_nix_error_class(err),
+    _ => unimplemented!(),
+  }
+}
+
+fn get_regex_error_class(error: &regex::Error) -> &'static str {
+  use regex::Error::*;
+  match error {
+    Syntax(_) => "SyntaxError",
+    CompiledTooBig(_) => "RangeError",
+    _ => "Error",
+  }
+}
+
+fn get_request_error_class(error: &reqwest::Error) -> &'static str {
+  error
+    .source()
+    .and_then(|inner_err| {
+      (inner_err
+        .downcast_ref::<io::Error>()
+        .map(get_io_error_class))
+      .or_else(|| {
+        inner_err
+          .downcast_ref::<serde_json::error::Error>()
+          .map(get_serde_json_error_class)
+      })
+      .or_else(|| {
+        inner_err
+          .downcast_ref::<url::ParseError>()
+          .map(get_url_parse_error_class)
+      })
+    })
+    .unwrap_or("Http")
+}
+
+fn get_serde_json_error_class(
+  error: &serde_json::error::Error,
+) -> &'static str {
+  use serde_json::error::*;
+  match error.classify() {
+    Category::Io => error
+      .source()
+      .and_then(|e| e.downcast_ref::<io::Error>())
+      .map(get_io_error_class)
+      .unwrap(),
+    Category::Syntax => "SyntaxError",
+    Category::Data => "InvalidData",
+    Category::Eof => "UnexpectedEof",
+  }
+}
+
+fn get_swc_diagnostic_class(_: &SwcDiagnosticBuffer) -> &'static str {
+  "SyntaxError"
+}
+
+fn get_url_parse_error_class(_error: &url::ParseError) -> &'static str {
+  "URIError"
+}
+
+#[cfg(unix)]
+fn get_nix_error_class(error: &nix::Error) -> &'static str {
+  use nix::errno::Errno::*;
+  match error {
+    nix::Error::Sys(EPERM) => "PermissionDenied",
+    nix::Error::Sys(EINVAL) => "TypeError",
+    nix::Error::Sys(ENOENT) => "NotFound",
+    nix::Error::Sys(ENOTTY) => "BadResource",
+    nix::Error::Sys(UnknownErrno) => unreachable!(),
+    nix::Error::Sys(_) => unreachable!(),
+    nix::Error::InvalidPath => "TypeError",
+    nix::Error::InvalidUtf8 => "InvalidData",
+    nix::Error::UnsupportedOperation => unreachable!(),
+  }
+}
+
+pub fn get_error_class(e: &ErrBox) -> &'static str {
+  use ErrBox::*;
+  match e {
+    Simple { class, .. } => Some(*class),
+    _ => None,
+  }
+  .or_else(|| {
+    e.downcast_ref::<dlopen::Error>()
+      .map(get_dlopen_error_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<env::VarError>()
+      .map(get_env_var_error_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<ImportMapError>()
+      .map(get_import_map_error_class)
+  })
+  .or_else(|| e.downcast_ref::<io::Error>().map(get_io_error_class))
+  .or_else(|| {
+    e.downcast_ref::<ModuleResolutionError>()
+      .map(get_module_resolution_error_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<notify::Error>()
+      .map(get_notify_error_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<ReadlineError>()
+      .map(get_readline_error_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<reqwest::Error>()
+      .map(get_request_error_class)
+  })
+  .or_else(|| e.downcast_ref::<regex::Error>().map(get_regex_error_class))
+  .or_else(|| {
+    e.downcast_ref::<serde_json::error::Error>()
+      .map(get_serde_json_error_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<SwcDiagnosticBuffer>()
+      .map(get_swc_diagnostic_class)
+  })
+  .or_else(|| {
+    e.downcast_ref::<url::ParseError>()
+      .map(get_url_parse_error_class)
+  })
+  .or_else(|| {
+    #[cfg(unix)]
+    let maybe_get_nix_error_class =
+      || e.downcast_ref::<nix::Error>().map(get_nix_error_class);
+    #[cfg(not(unix))]
+    let maybe_get_nix_error_class = || Option::<&'static str>::None;
+    (maybe_get_nix_error_class)()
+  })
+  .unwrap_or_else(|| {
+    panic!("ErrBox '{}' contains boxed error of unknown type", e);
+  })
+}
+
+pub fn rust_err_to_json(error: &ErrBox) -> Box<[u8]> {
+  let error_value =
+    json!({ "kind": get_error_class(error), "message": error.to_string()});
+  serde_json::to_vec(&error_value).unwrap().into_boxed_slice()
+}
diff --git a/cli/file_fetcher.rs b/cli/file_fetcher.rs
index c703bfc27..c5fd78897 100644
--- a/cli/file_fetcher.rs
+++ b/cli/file_fetcher.rs
@@ -5,7 +5,6 @@ use crate::http_util;
 use crate::http_util::create_http_client;
 use crate::http_util::FetchOnceResult;
 use crate::msg;
-use crate::op_error::OpError;
 use crate::permissions::Permissions;
 use crate::text_encoding;
 use deno_core::ErrBox;
@@ -138,11 +137,12 @@ impl SourceFileFetcher {
 
   pub fn check_if_supported_scheme(url: &Url) -> Result<(), ErrBox> {
     if !SUPPORTED_URL_SCHEMES.contains(&url.scheme()) {
-      return Err(
-        OpError::other(
-          format!("Unsupported scheme \"{}\" for module \"{}\". Supported schemes: {:#?}", url.scheme(), url, SUPPORTED_URL_SCHEMES),
-        ).into()
-      );
+      return Err(ErrBox::error(format!(
+        "Unsupported scheme \"{}\" for module \"{}\". Supported schemes: {:#?}",
+        url.scheme(),
+        url,
+        SUPPORTED_URL_SCHEMES
+      )));
     }
 
     Ok(())
@@ -255,13 +255,13 @@ impl SourceFileFetcher {
             r#"Cannot find module "{}"{} in cache, --cached-only is specified"#,
             module_url, referrer_suffix
           );
-          OpError::not_found(msg).into()
+          ErrBox::new("NotFound", msg)
         } else if is_not_found {
           let msg = format!(
             r#"Cannot resolve module "{}"{}"#,
             module_url, referrer_suffix
           );
-          OpError::not_found(msg).into()
+          ErrBox::new("NotFound", msg)
         } else {
           err
         };
@@ -346,9 +346,7 @@ impl SourceFileFetcher {
     permissions: &Permissions,
   ) -> Result<SourceFile, ErrBox> {
     let filepath = module_url.to_file_path().map_err(|()| {
-      ErrBox::from(OpError::uri_error(
-        "File URL contains invalid path".to_owned(),
-      ))
+      ErrBox::new("URIError", "File URL contains invalid path")
     })?;
 
     permissions.check_read(&filepath)?;
@@ -385,8 +383,7 @@ impl SourceFileFetcher {
     redirect_limit: i64,
   ) -> Result<Option<SourceFile>, ErrBox> {
     if redirect_limit < 0 {
-      let e = OpError::http("too many redirects".to_string());
-      return Err(e.into());
+      return Err(ErrBox::new("Http", "too many redirects"));
     }
 
     let result = self.http_cache.get(&module_url);
@@ -451,12 +448,12 @@ impl SourceFileFetcher {
     permissions: &Permissions,
   ) -> Pin<Box<dyn Future<Output = Result<SourceFile, ErrBox>>>> {
     if redirect_limit < 0 {
-      let e = OpError::http("too many redirects".to_string());
-      return futures::future::err(e.into()).boxed_local();
+      let e = ErrBox::new("Http", "too many redirects");
+      return futures::future::err(e).boxed_local();
     }
 
     if let Err(e) = permissions.check_net_url(&module_url) {
-      return futures::future::err(e.into()).boxed_local();
+      return futures::future::err(e).boxed_local();
     }
 
     let is_blocked =
@@ -479,17 +476,12 @@ impl SourceFileFetcher {
     // If file wasn't found in cache check if we can fetch it
     if cached_only {
       // We can't fetch remote file - bail out
-      return futures::future::err(
-        std::io::Error::new(
-          std::io::ErrorKind::NotFound,
-          format!(
-            "Cannot find remote file '{}' in cache, --cached-only is specified",
-            module_url.to_string()
-          ),
-        )
-        .into(),
-      )
-      .boxed_local();
+      let message = format!(
+        "Cannot find remote file '{}' in cache, --cached-only is specified",
+        module_url
+      );
+      return futures::future::err(ErrBox::new("NotFound", message))
+        .boxed_local();
     }
 
     info!("{} {}", colors::green("Download"), module_url.to_string());
diff --git a/cli/fmt.rs b/cli/fmt.rs
index 319f7fece..b81573294 100644
--- a/cli/fmt.rs
+++ b/cli/fmt.rs
@@ -10,7 +10,6 @@
 use crate::colors;
 use crate::diff::diff;
 use crate::fs::files_in_subtree;
-use crate::op_error::OpError;
 use crate::text_encoding;
 use deno_core::ErrBox;
 use dprint_plugin_typescript as dprint;
@@ -110,14 +109,11 @@ async fn check_source_files(
   if not_formatted_files_count == 0 {
     Ok(())
   } else {
-    Err(
-      OpError::other(format!(
-        "Found {} not formatted {}",
-        not_formatted_files_count,
-        files_str(not_formatted_files_count),
-      ))
-      .into(),
-    )
+    Err(ErrBox::error(format!(
+      "Found {} not formatted {}",
+      not_formatted_files_count,
+      files_str(not_formatted_files_count),
+    )))
   }
 }
 
@@ -175,7 +171,7 @@ async fn format_source_files(
 fn format_stdin(check: bool) -> Result<(), ErrBox> {
   let mut source = String::new();
   if stdin().read_to_string(&mut source).is_err() {
-    return Err(OpError::other("Failed to read from stdin".to_string()).into());
+    return Err(ErrBox::error("Failed to read from stdin"));
   }
   let formatter = dprint::Formatter::new(get_config());
 
@@ -191,7 +187,7 @@ fn format_stdin(check: bool) -> Result<(), ErrBox> {
       }
     }
     Err(e) => {
-      return Err(OpError::other(e).into());
+      return Err(ErrBox::error(e));
     }
   }
   Ok(())
@@ -217,7 +213,9 @@ fn is_supported(path: &Path) -> bool {
   }
 }
 
-pub fn collect_files(files: Vec<String>) -> Result<Vec<PathBuf>, ErrBox> {
+pub fn collect_files(
+  files: Vec<String>,
+) -> Result<Vec<PathBuf>, std::io::Error> {
   let mut target_files: Vec<PathBuf> = vec![];
 
   if files.is_empty() {
diff --git a/cli/fmt_errors.rs b/cli/fmt_errors.rs
index 2d360892e..b2925f625 100644
--- a/cli/fmt_errors.rs
+++ b/cli/fmt_errors.rs
@@ -114,7 +114,7 @@ impl JSError {
   ) -> ErrBox {
     let core_js_error = apply_source_map(&core_js_error, source_map_getter);
     let js_error = Self(core_js_error);
-    ErrBox::from(js_error)
+    js_error.into()
   }
 }
 
diff --git a/cli/main.rs b/cli/main.rs
index 7cf698d5a..b19465713 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -29,6 +29,7 @@ pub mod deno_dir;
 pub mod diagnostics;
 mod diff;
 mod disk_cache;
+pub mod errors;
 mod file_fetcher;
 pub mod flags;
 mod flags_allow_net;
@@ -48,7 +49,6 @@ mod lockfile;
 mod metrics;
 mod module_graph;
 pub mod msg;
-pub mod op_error;
 mod op_fetch_asset;
 pub mod ops;
 pub mod permissions;
diff --git a/cli/module_graph.rs b/cli/module_graph.rs
index 5b15c0cd4..7cbd4cfcc 100644
--- a/cli/module_graph.rs
+++ b/cli/module_graph.rs
@@ -5,7 +5,6 @@ use crate::file_fetcher::SourceFile;
 use crate::file_fetcher::SourceFileFetcher;
 use crate::import_map::ImportMap;
 use crate::msg::MediaType;
-use crate::op_error::OpError;
 use crate::permissions::Permissions;
 use crate::swc_util::Location;
 use crate::tsc::pre_process_file;
@@ -37,7 +36,7 @@ fn err_with_location(e: ErrBox, maybe_location: Option<&Location>) -> ErrBox {
       location.filename, location.line
     );
     let err_str = e.to_string();
-    OpError::other(format!("{}{}", err_str, location_str)).into()
+    ErrBox::error(format!("{}{}", err_str, location_str))
   } else {
     e
   }
@@ -52,10 +51,10 @@ fn validate_no_downgrade(
   if let Some(referrer) = maybe_referrer.as_ref() {
     if let "https" = referrer.as_url().scheme() {
       if let "http" = module_specifier.as_url().scheme() {
-        let e = OpError::permission_denied(
-          "Modules loaded over https:// are not allowed to import modules over http://".to_string()
+        let e = ErrBox::new("PermissionDenied",
+          "Modules loaded over https:// are not allowed to import modules over http://"
         );
-        return Err(err_with_location(e.into(), maybe_location));
+        return Err(err_with_location(e, maybe_location));
       };
     };
   };
@@ -77,10 +76,10 @@ fn validate_no_file_from_remote(
         match specifier_url.scheme() {
           "http" | "https" => {}
           _ => {
-            let e = OpError::permission_denied(
+            let e = ErrBox::new("PermissionDenied",
               "Remote modules are not allowed to statically import local modules. Use dynamic import instead.".to_string()
             );
-            return Err(err_with_location(e.into(), maybe_location));
+            return Err(err_with_location(e, maybe_location));
           }
         }
       }
diff --git a/cli/op_error.rs b/cli/op_error.rs
deleted file mode 100644
index 32ad9c0f7..000000000
--- a/cli/op_error.rs
+++ /dev/null
@@ -1,550 +0,0 @@
-// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-
-//! There are many types of errors in Deno:
-//! - ErrBox: a generic boxed object. This is the super type of all
-//!   errors handled in Rust.
-//! - JSError: a container for the error message and stack trace for exceptions
-//!   thrown in JavaScript code. We use this to pretty-print stack traces.
-//! - OpError: these are errors that happen during ops, which are passed
-//!   back into the runtime, where an exception object is created and thrown.
-//!   OpErrors have an integer code associated with them - access this via the
-//!   `kind` field.
-//! - Diagnostic: these are errors that originate in TypeScript's compiler.
-//!   They're similar to JSError, in that they have line numbers.
-//!   But Diagnostics are compile-time type errors, whereas JSErrors are runtime
-//!   exceptions.
-
-use crate::import_map::ImportMapError;
-use crate::swc_util::SwcDiagnosticBuffer;
-use deno_core::ErrBox;
-use deno_core::ModuleResolutionError;
-use rustyline::error::ReadlineError;
-use std::env::VarError;
-use std::error::Error;
-use std::fmt;
-use std::io;
-
-// Warning! The values in this enum are duplicated in js/errors.ts
-// Update carefully!
-#[derive(Clone, Copy, PartialEq, Debug)]
-pub enum ErrorKind {
-  NotFound = 1,
-  PermissionDenied = 2,
-  ConnectionRefused = 3,
-  ConnectionReset = 4,
-  ConnectionAborted = 5,
-  NotConnected = 6,
-  AddrInUse = 7,
-  AddrNotAvailable = 8,
-  BrokenPipe = 9,
-  AlreadyExists = 10,
-  InvalidData = 13,
-  TimedOut = 14,
-  Interrupted = 15,
-  WriteZero = 16,
-  UnexpectedEof = 17,
-  BadResource = 18,
-  Http = 19,
-  URIError = 20,
-  TypeError = 21,
-  /// This maps to window.Error - ie. a generic error type
-  /// if no better context is available.
-  /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error
-  Other = 22,
-  Busy = 23,
-}
-
-impl From<ErrorKind> for String {
-  fn from(kind: ErrorKind) -> Self {
-    let s = match kind {
-      ErrorKind::NotFound => "NotFound",
-      ErrorKind::PermissionDenied => "PermissionDenied",
-      ErrorKind::ConnectionRefused => "ConnectionRefused",
-      ErrorKind::ConnectionReset => "ConnectionReset",
-      ErrorKind::ConnectionAborted => "ConnectionAborted",
-      ErrorKind::NotConnected => "NotConnected",
-      ErrorKind::AddrInUse => "AddrInUse",
-      ErrorKind::AddrNotAvailable => "AddrNotAvailable",
-      ErrorKind::BrokenPipe => "BrokenPipe",
-      ErrorKind::AlreadyExists => "AlreadyExists",
-      ErrorKind::InvalidData => "InvalidData",
-      ErrorKind::TimedOut => "TimedOut",
-      ErrorKind::Interrupted => "Interrupted",
-      ErrorKind::WriteZero => "WriteZero",
-      ErrorKind::UnexpectedEof => "UnexpectedEof",
-      ErrorKind::BadResource => "BadResource",
-      ErrorKind::Http => "Http",
-      ErrorKind::URIError => "URIError",
-      ErrorKind::TypeError => "TypeError",
-      ErrorKind::Other => "Other",
-      ErrorKind::Busy => "Busy",
-    };
-
-    s.to_string()
-  }
-}
-
-fn error_str_to_kind(kind_str: &str) -> ErrorKind {
-  match kind_str {
-    "NotFound" => ErrorKind::NotFound,
-    "PermissionDenied" => ErrorKind::PermissionDenied,
-    "ConnectionRefused" => ErrorKind::ConnectionRefused,
-    "ConnectionReset" => ErrorKind::ConnectionReset,
-    "ConnectionAborted" => ErrorKind::ConnectionAborted,
-    "NotConnected" => ErrorKind::NotConnected,
-    "AddrInUse" => ErrorKind::AddrInUse,
-    "AddrNotAvailable" => ErrorKind::AddrNotAvailable,
-    "BrokenPipe" => ErrorKind::BrokenPipe,
-    "AlreadyExists" => ErrorKind::AlreadyExists,
-    "InvalidData" => ErrorKind::InvalidData,
-    "TimedOut" => ErrorKind::TimedOut,
-    "Interrupted" => ErrorKind::Interrupted,
-    "WriteZero" => ErrorKind::WriteZero,
-    "UnexpectedEof" => ErrorKind::UnexpectedEof,
-    "BadResource" => ErrorKind::BadResource,
-    "Http" => ErrorKind::Http,
-    "URIError" => ErrorKind::URIError,
-    "TypeError" => ErrorKind::TypeError,
-    "Other" => ErrorKind::Other,
-    "Busy" => ErrorKind::Busy,
-    _ => panic!("unknown error kind"),
-  }
-}
-
-#[derive(Debug)]
-pub struct OpError {
-  pub kind_str: String,
-  pub msg: String,
-}
-
-impl OpError {
-  fn new(kind: ErrorKind, msg: String) -> Self {
-    Self {
-      kind_str: kind.into(),
-      msg,
-    }
-  }
-
-  pub fn not_found(msg: String) -> Self {
-    Self::new(ErrorKind::NotFound, msg)
-  }
-
-  pub fn not_implemented() -> Self {
-    Self::other("not implemented".to_string())
-  }
-
-  pub fn other(msg: String) -> Self {
-    Self::new(ErrorKind::Other, msg)
-  }
-
-  pub fn type_error(msg: String) -> Self {
-    Self::new(ErrorKind::TypeError, msg)
-  }
-
-  pub fn http(msg: String) -> Self {
-    Self::new(ErrorKind::Http, msg)
-  }
-
-  pub fn uri_error(msg: String) -> Self {
-    Self::new(ErrorKind::URIError, msg)
-  }
-
-  pub fn permission_denied(msg: String) -> OpError {
-    Self::new(ErrorKind::PermissionDenied, msg)
-  }
-
-  pub fn bad_resource(msg: String) -> OpError {
-    Self::new(ErrorKind::BadResource, msg)
-  }
-
-  // BadResource usually needs no additional detail, hence this helper.
-  pub fn bad_resource_id() -> OpError {
-    Self::new(ErrorKind::BadResource, "Bad resource ID".to_string())
-  }
-
-  pub fn invalid_utf8() -> OpError {
-    Self::new(ErrorKind::InvalidData, "invalid utf8".to_string())
-  }
-
-  pub fn resource_unavailable() -> OpError {
-    Self::new(
-      ErrorKind::Busy,
-      "resource is unavailable because it is in use by a promise".to_string(),
-    )
-  }
-
-  pub fn invalid_domain_error() -> OpError {
-    OpError::type_error("Invalid domain.".to_string())
-  }
-
-  pub fn permission_escalation_error() -> OpError {
-    OpError::permission_denied(
-      "Arguments escalate parent permissions.".to_string(),
-    )
-  }
-}
-
-impl Error for OpError {}
-
-impl fmt::Display for OpError {
-  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    f.pad(self.msg.as_str())
-  }
-}
-
-impl From<ImportMapError> for OpError {
-  fn from(error: ImportMapError) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&ImportMapError> for OpError {
-  fn from(error: &ImportMapError) -> Self {
-    Self::new(ErrorKind::Other, error.to_string())
-  }
-}
-
-impl From<ModuleResolutionError> for OpError {
-  fn from(error: ModuleResolutionError) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&ModuleResolutionError> for OpError {
-  fn from(error: &ModuleResolutionError) -> Self {
-    Self::new(ErrorKind::URIError, error.to_string())
-  }
-}
-
-impl From<VarError> for OpError {
-  fn from(error: VarError) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&VarError> for OpError {
-  fn from(error: &VarError) -> Self {
-    use VarError::*;
-    let kind = match error {
-      NotPresent => ErrorKind::NotFound,
-      NotUnicode(..) => ErrorKind::InvalidData,
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-impl From<io::Error> for OpError {
-  fn from(error: io::Error) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&io::Error> for OpError {
-  fn from(error: &io::Error) -> Self {
-    use io::ErrorKind::*;
-    let kind = match error.kind() {
-      NotFound => ErrorKind::NotFound,
-      PermissionDenied => ErrorKind::PermissionDenied,
-      ConnectionRefused => ErrorKind::ConnectionRefused,
-      ConnectionReset => ErrorKind::ConnectionReset,
-      ConnectionAborted => ErrorKind::ConnectionAborted,
-      NotConnected => ErrorKind::NotConnected,
-      AddrInUse => ErrorKind::AddrInUse,
-      AddrNotAvailable => ErrorKind::AddrNotAvailable,
-      BrokenPipe => ErrorKind::BrokenPipe,
-      AlreadyExists => ErrorKind::AlreadyExists,
-      InvalidInput => ErrorKind::TypeError,
-      InvalidData => ErrorKind::InvalidData,
-      TimedOut => ErrorKind::TimedOut,
-      Interrupted => ErrorKind::Interrupted,
-      WriteZero => ErrorKind::WriteZero,
-      UnexpectedEof => ErrorKind::UnexpectedEof,
-      Other => ErrorKind::Other,
-      WouldBlock => unreachable!(),
-      // Non-exhaustive enum - might add new variants
-      // in the future
-      _ => unreachable!(),
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-impl From<url::ParseError> for OpError {
-  fn from(error: url::ParseError) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&url::ParseError> for OpError {
-  fn from(error: &url::ParseError) -> Self {
-    Self::new(ErrorKind::URIError, error.to_string())
-  }
-}
-impl From<reqwest::Error> for OpError {
-  fn from(error: reqwest::Error) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&reqwest::Error> for OpError {
-  fn from(error: &reqwest::Error) -> Self {
-    match error.source() {
-      Some(err_ref) => None
-        .or_else(|| {
-          err_ref
-            .downcast_ref::<url::ParseError>()
-            .map(|e| e.clone().into())
-        })
-        .or_else(|| {
-          err_ref
-            .downcast_ref::<io::Error>()
-            .map(|e| e.to_owned().into())
-        })
-        .or_else(|| {
-          err_ref
-            .downcast_ref::<serde_json::error::Error>()
-            .map(|e| e.into())
-        })
-        .unwrap_or_else(|| Self::new(ErrorKind::Http, error.to_string())),
-      None => Self::new(ErrorKind::Http, error.to_string()),
-    }
-  }
-}
-
-impl From<ReadlineError> for OpError {
-  fn from(error: ReadlineError) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&ReadlineError> for OpError {
-  fn from(error: &ReadlineError) -> Self {
-    use ReadlineError::*;
-    let kind = match error {
-      Io(err) => return OpError::from(err),
-      Eof => ErrorKind::UnexpectedEof,
-      Interrupted => ErrorKind::Interrupted,
-      #[cfg(unix)]
-      Errno(err) => return (*err).into(),
-      _ => unimplemented!(),
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-impl From<serde_json::error::Error> for OpError {
-  fn from(error: serde_json::error::Error) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&serde_json::error::Error> for OpError {
-  fn from(error: &serde_json::error::Error) -> Self {
-    use serde_json::error::*;
-    let kind = match error.classify() {
-      Category::Io => ErrorKind::TypeError,
-      Category::Syntax => ErrorKind::TypeError,
-      Category::Data => ErrorKind::InvalidData,
-      Category::Eof => ErrorKind::UnexpectedEof,
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-#[cfg(unix)]
-impl From<nix::Error> for OpError {
-  fn from(error: nix::Error) -> Self {
-    use nix::errno::Errno::*;
-    let kind = match error {
-      nix::Error::Sys(EPERM) => ErrorKind::PermissionDenied,
-      nix::Error::Sys(EINVAL) => ErrorKind::TypeError,
-      nix::Error::Sys(ENOENT) => ErrorKind::NotFound,
-      nix::Error::Sys(ENOTTY) => ErrorKind::BadResource,
-      nix::Error::Sys(UnknownErrno) => unreachable!(),
-      nix::Error::Sys(_) => unreachable!(),
-      nix::Error::InvalidPath => ErrorKind::TypeError,
-      nix::Error::InvalidUtf8 => ErrorKind::InvalidData,
-      nix::Error::UnsupportedOperation => unreachable!(),
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-impl From<dlopen::Error> for OpError {
-  fn from(error: dlopen::Error) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&dlopen::Error> for OpError {
-  fn from(error: &dlopen::Error) -> Self {
-    use dlopen::Error::*;
-    let kind = match error {
-      NullCharacter(_) => ErrorKind::Other,
-      OpeningLibraryError(e) => return e.into(),
-      SymbolGettingError(e) => return e.into(),
-      AddrNotMatchingDll(e) => return e.into(),
-      NullSymbol => ErrorKind::Other,
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-impl From<notify::Error> for OpError {
-  fn from(error: notify::Error) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&notify::Error> for OpError {
-  fn from(error: &notify::Error) -> Self {
-    use notify::ErrorKind::*;
-    let kind = match error.kind {
-      Generic(_) => ErrorKind::Other,
-      Io(ref e) => return e.into(),
-      PathNotFound => ErrorKind::NotFound,
-      WatchNotFound => ErrorKind::NotFound,
-      InvalidConfig(_) => ErrorKind::InvalidData,
-    };
-
-    Self::new(kind, error.to_string())
-  }
-}
-
-impl From<SwcDiagnosticBuffer> for OpError {
-  fn from(error: SwcDiagnosticBuffer) -> Self {
-    OpError::from(&error)
-  }
-}
-
-impl From<&SwcDiagnosticBuffer> for OpError {
-  fn from(error: &SwcDiagnosticBuffer) -> Self {
-    Self::new(ErrorKind::Other, error.diagnostics.join(", "))
-  }
-}
-
-impl From<ErrBox> for OpError {
-  fn from(error: ErrBox) -> Self {
-    #[cfg(unix)]
-    fn unix_error_kind(err: &ErrBox) -> Option<OpError> {
-      err.downcast_ref::<nix::Error>().map(|e| (*e).into())
-    }
-
-    #[cfg(not(unix))]
-    fn unix_error_kind(_: &ErrBox) -> Option<OpError> {
-      None
-    }
-
-    None
-      .or_else(|| {
-        error.downcast_ref::<OpError>().map(|e| {
-          OpError::new(error_str_to_kind(&e.kind_str), e.msg.to_string())
-        })
-      })
-      .or_else(|| error.downcast_ref::<reqwest::Error>().map(|e| e.into()))
-      .or_else(|| error.downcast_ref::<ImportMapError>().map(|e| e.into()))
-      .or_else(|| error.downcast_ref::<io::Error>().map(|e| e.into()))
-      .or_else(|| {
-        error
-          .downcast_ref::<ModuleResolutionError>()
-          .map(|e| e.into())
-      })
-      .or_else(|| error.downcast_ref::<url::ParseError>().map(|e| e.into()))
-      .or_else(|| error.downcast_ref::<VarError>().map(|e| e.into()))
-      .or_else(|| error.downcast_ref::<ReadlineError>().map(|e| e.into()))
-      .or_else(|| {
-        error
-          .downcast_ref::<serde_json::error::Error>()
-          .map(|e| e.into())
-      })
-      .or_else(|| error.downcast_ref::<dlopen::Error>().map(|e| e.into()))
-      .or_else(|| error.downcast_ref::<notify::Error>().map(|e| e.into()))
-      .or_else(|| {
-        error
-          .downcast_ref::<SwcDiagnosticBuffer>()
-          .map(|e| e.into())
-      })
-      .or_else(|| unix_error_kind(&error))
-      .unwrap_or_else(|| {
-        panic!("Can't downcast {:?} to OpError", error);
-      })
-  }
-}
-
-#[cfg(test)]
-mod tests {
-  use super::*;
-
-  fn io_error() -> io::Error {
-    io::Error::from(io::ErrorKind::NotFound)
-  }
-
-  fn url_error() -> url::ParseError {
-    url::ParseError::EmptyHost
-  }
-
-  fn import_map_error() -> ImportMapError {
-    ImportMapError {
-      msg: "an import map error".to_string(),
-    }
-  }
-
-  #[test]
-  fn test_simple_error() {
-    let err = OpError::not_found("foo".to_string());
-    assert_eq!(err.kind_str, "NotFound");
-    assert_eq!(err.to_string(), "foo");
-  }
-
-  #[test]
-  fn test_io_error() {
-    let err = OpError::from(io_error());
-    assert_eq!(err.kind_str, "NotFound");
-    assert_eq!(err.to_string(), "entity not found");
-  }
-
-  #[test]
-  fn test_url_error() {
-    let err = OpError::from(url_error());
-    assert_eq!(err.kind_str, "URIError");
-    assert_eq!(err.to_string(), "empty host");
-  }
-
-  // TODO find a way to easily test tokio errors and unix errors
-
-  #[test]
-  fn test_import_map_error() {
-    let err = OpError::from(import_map_error());
-    assert_eq!(err.kind_str, "Other");
-    assert_eq!(err.to_string(), "an import map error");
-  }
-
-  #[test]
-  fn test_bad_resource() {
-    let err = OpError::bad_resource("Resource has been closed".to_string());
-    assert_eq!(err.kind_str, "BadResource");
-    assert_eq!(err.to_string(), "Resource has been closed");
-  }
-
-  #[test]
-  fn test_bad_resource_id() {
-    let err = OpError::bad_resource_id();
-    assert_eq!(err.kind_str, "BadResource");
-    assert_eq!(err.to_string(), "Bad resource ID");
-  }
-
-  #[test]
-  fn test_permission_denied() {
-    let err = OpError::permission_denied(
-      "run again with the --allow-net flag".to_string(),
-    );
-    assert_eq!(err.kind_str, "PermissionDenied");
-    assert_eq!(err.to_string(), "run again with the --allow-net flag");
-  }
-}
diff --git a/cli/ops/compiler.rs b/cli/ops/compiler.rs
index 7ad4aece3..c35043e2d 100644
--- a/cli/ops/compiler.rs
+++ b/cli/ops/compiler.rs
@@ -1,10 +1,10 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{JsonOp, Value};
-use crate::op_error::OpError;
 use crate::ops::json_op;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::rc::Rc;
 use std::sync::Arc;
@@ -36,18 +36,18 @@ pub fn compiler_op<D>(
   &mut deno_core::CoreIsolateState,
   Value,
   &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError>
+) -> Result<JsonOp, ErrBox>
 where
   D: Fn(
     Arc<Mutex<Option<String>>>,
     Value,
     &mut [ZeroCopyBuf],
-  ) -> Result<JsonOp, OpError>,
+  ) -> Result<JsonOp, ErrBox>,
 {
   move |_isolate_state: &mut CoreIsolateState,
         args: Value,
         zero_copy: &mut [ZeroCopyBuf]|
-        -> Result<JsonOp, OpError> {
+        -> Result<JsonOp, ErrBox> {
     dispatcher(response.clone(), args, zero_copy)
   }
 }
@@ -56,7 +56,7 @@ fn op_compiler_respond(
   response: Arc<Mutex<Option<String>>>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let mut r = response.lock().unwrap();
   assert!(
     r.is_none(),
diff --git a/cli/ops/dispatch_json.rs b/cli/ops/dispatch_json.rs
index 5ed7e6c6d..6e0eddac8 100644
--- a/cli/ops/dispatch_json.rs
+++ b/cli/ops/dispatch_json.rs
@@ -1,7 +1,7 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-use crate::op_error::OpError;
 use deno_core::Buf;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::Op;
 use deno_core::ZeroCopyBuf;
 use futures::future::FutureExt;
@@ -11,7 +11,7 @@ pub use serde_json::Value;
 use std::future::Future;
 use std::pin::Pin;
 
-pub type JsonResult = Result<Value, OpError>;
+pub type JsonResult = Result<Value, ErrBox>;
 
 pub type AsyncJsonOp = Pin<Box<dyn Future<Output = JsonResult>>>;
 
@@ -23,17 +23,18 @@ pub enum JsonOp {
   AsyncUnref(AsyncJsonOp),
 }
 
-fn json_err(err: OpError) -> Value {
-  json!({
-    "message": err.msg,
-    "kind": err.kind_str,
-  })
-}
-
-pub fn serialize_result(promise_id: Option<u64>, result: JsonResult) -> Buf {
+pub fn serialize_result(
+  rust_err_to_json_fn: &'static dyn deno_core::RustErrToJsonFn,
+  promise_id: Option<u64>,
+  result: JsonResult,
+) -> Buf {
   let value = match result {
     Ok(v) => json!({ "ok": v, "promiseId": promise_id }),
-    Err(err) => json!({ "err": json_err(err), "promiseId": promise_id }),
+    Err(err) => {
+      let serialized_err = (&rust_err_to_json_fn)(&err);
+      let err_value: Value = serde_json::from_slice(&serialized_err).unwrap();
+      json!({ "err": err_value, "promiseId": promise_id })
+    }
   };
   serde_json::to_vec(&value).unwrap().into_boxed_slice()
 }
@@ -52,14 +53,15 @@ where
     &mut CoreIsolateState,
     Value,
     &mut [ZeroCopyBuf],
-  ) -> Result<JsonOp, OpError>,
+  ) -> Result<JsonOp, ErrBox>,
 {
   move |isolate_state: &mut CoreIsolateState, zero_copy: &mut [ZeroCopyBuf]| {
     assert!(!zero_copy.is_empty(), "Expected JSON string at position 0");
+    let rust_err_to_json_fn = isolate_state.rust_err_to_json_fn;
     let async_args: AsyncArgs = match serde_json::from_slice(&zero_copy[0]) {
       Ok(args) => args,
       Err(e) => {
-        let buf = serialize_result(None, Err(OpError::from(e)));
+        let buf = serialize_result(rust_err_to_json_fn, None, Err(e.into()));
         return Op::Sync(buf);
       }
     };
@@ -67,31 +69,44 @@ where
     let is_sync = promise_id.is_none();
 
     let result = serde_json::from_slice(&zero_copy[0])
-      .map_err(OpError::from)
+      .map_err(ErrBox::from)
       .and_then(|args| d(isolate_state, args, &mut zero_copy[1..]));
 
     // Convert to Op
     match result {
       Ok(JsonOp::Sync(sync_value)) => {
         assert!(promise_id.is_none());
-        Op::Sync(serialize_result(promise_id, Ok(sync_value)))
+        Op::Sync(serialize_result(
+          rust_err_to_json_fn,
+          promise_id,
+          Ok(sync_value),
+        ))
       }
       Ok(JsonOp::Async(fut)) => {
         assert!(promise_id.is_some());
         let fut2 = fut.then(move |result| {
-          futures::future::ready(serialize_result(promise_id, result))
+          futures::future::ready(serialize_result(
+            rust_err_to_json_fn,
+            promise_id,
+            result,
+          ))
         });
         Op::Async(fut2.boxed_local())
       }
       Ok(JsonOp::AsyncUnref(fut)) => {
         assert!(promise_id.is_some());
         let fut2 = fut.then(move |result| {
-          futures::future::ready(serialize_result(promise_id, result))
+          futures::future::ready(serialize_result(
+            rust_err_to_json_fn,
+            promise_id,
+            result,
+          ))
         });
         Op::AsyncUnref(fut2.boxed_local())
       }
       Err(sync_err) => {
-        let buf = serialize_result(promise_id, Err(sync_err));
+        let buf =
+          serialize_result(rust_err_to_json_fn, promise_id, Err(sync_err));
         if is_sync {
           Op::Sync(buf)
         } else {
@@ -102,7 +117,7 @@ where
   }
 }
 
-pub fn blocking_json<F>(is_sync: bool, f: F) -> Result<JsonOp, OpError>
+pub fn blocking_json<F>(is_sync: bool, f: F) -> Result<JsonOp, ErrBox>
 where
   F: 'static + Send + FnOnce() -> JsonResult,
 {
diff --git a/cli/ops/dispatch_minimal.rs b/cli/ops/dispatch_minimal.rs
index df7d48b4e..b0dc7ad8a 100644
--- a/cli/ops/dispatch_minimal.rs
+++ b/cli/ops/dispatch_minimal.rs
@@ -4,19 +4,22 @@
 //! alternative to flatbuffers using a very simple list of int32s to lay out
 //! messages. The first i32 is used to determine if a message a flatbuffer
 //! message or a "minimal" message.
-use crate::op_error::OpError;
-use byteorder::{LittleEndian, WriteBytesExt};
+use crate::errors::get_error_class;
 use deno_core::Buf;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::Op;
 use deno_core::ZeroCopyBuf;
 use futures::future::FutureExt;
 use std::future::Future;
+use std::iter::repeat;
+use std::mem::size_of_val;
 use std::pin::Pin;
+use std::slice;
 
 pub enum MinimalOp {
-  Sync(Result<i32, OpError>),
-  Async(Pin<Box<dyn Future<Output = Result<i32, OpError>>>>),
+  Sync(Result<i32, ErrBox>),
+  Async(Pin<Box<dyn Future<Output = Result<i32, ErrBox>>>>),
 }
 
 #[derive(Copy, Clone, Debug, PartialEq)]
@@ -40,24 +43,38 @@ pub struct ErrorRecord {
   pub promise_id: i32,
   pub arg: i32,
   pub error_len: i32,
-  pub error_code: Vec<u8>,
+  pub error_class: &'static [u8],
   pub error_message: Vec<u8>,
 }
 
 impl Into<Buf> for ErrorRecord {
   fn into(self) -> Buf {
-    let v32: Vec<i32> = vec![self.promise_id, self.arg, self.error_len];
-    let mut v8: Vec<u8> = Vec::new();
-    for n in v32 {
-      v8.write_i32::<LittleEndian>(n).unwrap();
-    }
-    let mut code = self.error_code;
-    let mut message = self.error_message;
-    v8.append(&mut code);
-    v8.append(&mut message);
-    // Align to 32bit word, padding with the space character.
-    v8.resize((v8.len() + 3usize) & !3usize, b' ');
-    v8.into_boxed_slice()
+    let Self {
+      promise_id,
+      arg,
+      error_len,
+      error_class,
+      error_message,
+      ..
+    } = self;
+    let header_i32 = [promise_id, arg, error_len];
+    let header_u8 = unsafe {
+      slice::from_raw_parts(
+        &header_i32 as *const _ as *const u8,
+        size_of_val(&header_i32),
+      )
+    };
+    let padded_len =
+      (header_u8.len() + error_class.len() + error_message.len() + 3usize)
+        & !3usize;
+    header_u8
+      .iter()
+      .cloned()
+      .chain(error_class.iter().cloned())
+      .chain(error_message.into_iter())
+      .chain(repeat(b' '))
+      .take(padded_len)
+      .collect()
   }
 }
 
@@ -71,7 +88,7 @@ fn test_error_record() {
     promise_id: 1,
     arg: -1,
     error_len: 11,
-    error_code: "BadResource".to_string().as_bytes().to_owned(),
+    error_class: b"BadResource",
     error_message: "Error".to_string().as_bytes().to_owned(),
   };
   let buf: Buf = err_record.into();
@@ -129,13 +146,14 @@ where
     let mut record = match parse_min_record(&zero_copy[0]) {
       Some(r) => r,
       None => {
-        let e = OpError::type_error("Unparsable control buffer".to_string());
+        let error = ErrBox::type_error("Unparsable control buffer");
+        let error_class = get_error_class(&error);
         let error_record = ErrorRecord {
           promise_id: 0,
           arg: -1,
-          error_len: e.kind_str.len() as i32,
-          error_code: e.kind_str.as_bytes().to_owned(),
-          error_message: e.msg.as_bytes().to_owned(),
+          error_len: error_class.len() as i32,
+          error_class: error_class.as_bytes(),
+          error_message: error.to_string().as_bytes().to_owned(),
         };
         return Op::Sync(error_record.into());
       }
@@ -151,12 +169,13 @@ where
           record.into()
         }
         Err(err) => {
+          let error_class = get_error_class(&err);
           let error_record = ErrorRecord {
             promise_id: record.promise_id,
             arg: -1,
-            error_len: err.kind_str.len() as i32,
-            error_code: err.kind_str.as_bytes().to_owned(),
-            error_message: err.msg.as_bytes().to_owned(),
+            error_len: error_class.len() as i32,
+            error_class: error_class.as_bytes(),
+            error_message: err.to_string().as_bytes().to_owned(),
           };
           error_record.into()
         }
@@ -169,12 +188,13 @@ where
               record.into()
             }
             Err(err) => {
+              let error_class = get_error_class(&err);
               let error_record = ErrorRecord {
                 promise_id: record.promise_id,
                 arg: -1,
-                error_len: err.kind_str.len() as i32,
-                error_code: err.kind_str.as_bytes().to_owned(),
-                error_message: err.msg.as_bytes().to_owned(),
+                error_len: error_class.len() as i32,
+                error_class: error_class.as_bytes(),
+                error_message: err.to_string().as_bytes().to_owned(),
               };
               error_record.into()
             }
diff --git a/cli/ops/errors.rs b/cli/ops/errors.rs
index 02295d7f8..b9405fe54 100644
--- a/cli/ops/errors.rs
+++ b/cli/ops/errors.rs
@@ -1,11 +1,11 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use crate::diagnostics::Diagnostic;
-use crate::op_error::OpError;
 use crate::source_maps::get_orig_position;
 use crate::source_maps::CachedMaps;
 use crate::state::State;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::collections::HashMap;
 use std::rc::Rc;
@@ -33,7 +33,7 @@ fn op_apply_source_map(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ApplySourceMap = serde_json::from_value(args)?;
 
   let mut mappings_map: CachedMaps = HashMap::new();
@@ -57,7 +57,7 @@ fn op_format_diagnostic(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let diagnostic = serde_json::from_value::<Diagnostic>(args)?;
   Ok(JsonOp::Sync(json!(diagnostic.to_string())))
 }
diff --git a/cli/ops/fetch.rs b/cli/ops/fetch.rs
index b320222ed..c7bfaf9f1 100644
--- a/cli/ops/fetch.rs
+++ b/cli/ops/fetch.rs
@@ -2,10 +2,10 @@
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use super::io::{StreamResource, StreamResourceHolder};
 use crate::http_util::{create_http_client, HttpBody};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use futures::future::FutureExt;
 use http::header::HeaderName;
@@ -38,7 +38,7 @@ pub fn op_fetch(
   state: &Rc<State>,
   args: Value,
   data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: FetchArgs = serde_json::from_value(args)?;
   let url = args.url;
   let resource_table_ = isolate_state.resource_table.borrow();
@@ -47,7 +47,7 @@ pub fn op_fetch(
   let client = if let Some(rid) = args.client_rid {
     let r = resource_table_
       .get::<HttpClientResource>(rid)
-      .ok_or_else(OpError::bad_resource_id)?;
+      .ok_or_else(ErrBox::bad_resource_id)?;
     &r.client
   } else {
     client_ref_mut = state.http_client.borrow_mut();
@@ -55,17 +55,16 @@ pub fn op_fetch(
   };
 
   let method = match args.method {
-    Some(method_str) => Method::from_bytes(method_str.as_bytes())
-      .map_err(|e| OpError::other(e.to_string()))?,
+    Some(method_str) => Method::from_bytes(method_str.as_bytes())?,
     None => Method::GET,
   };
 
-  let url_ = url::Url::parse(&url).map_err(OpError::from)?;
+  let url_ = url::Url::parse(&url)?;
 
   // Check scheme before asking for net permission
   let scheme = url_.scheme();
   if scheme != "http" && scheme != "https" {
-    return Err(OpError::type_error(format!(
+    return Err(ErrBox::type_error(format!(
       "scheme '{}' not supported",
       scheme
     )));
@@ -142,7 +141,7 @@ fn op_create_http_client(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: CreateHttpClientOptions = serde_json::from_value(args)?;
   let mut resource_table = isolate_state.resource_table.borrow_mut();
 
diff --git a/cli/ops/fs.rs b/cli/ops/fs.rs
index 0fd6ad5ef..00736b813 100644
--- a/cli/ops/fs.rs
+++ b/cli/ops/fs.rs
@@ -3,12 +3,12 @@
 use super::dispatch_json::{blocking_json, Deserialize, JsonOp, Value};
 use super::io::std_file_resource;
 use super::io::{FileMetadata, StreamResource, StreamResourceHolder};
-use crate::op_error::OpError;
 use crate::ops::dispatch_json::JsonResult;
 use crate::state::State;
 use deno_core::BufVec;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ResourceTable;
 use deno_core::ZeroCopyBuf;
 use futures::future::FutureExt;
@@ -55,8 +55,11 @@ pub fn init(i: &mut CoreIsolate, s: &Rc<State>) {
   i.register_op("op_utime", s.stateful_json_op(op_utime));
 }
 
-fn into_string(s: std::ffi::OsString) -> Result<String, OpError> {
-  s.into_string().map_err(|_| OpError::invalid_utf8())
+fn into_string(s: std::ffi::OsString) -> Result<String, ErrBox> {
+  s.into_string().map_err(|s| {
+    let message = format!("File name or path {:?} is not valid UTF-8", s);
+    ErrBox::new("InvalidData", message)
+  })
 }
 
 #[derive(Deserialize)]
@@ -82,7 +85,7 @@ struct OpenOptions {
 fn open_helper(
   state: &State,
   args: Value,
-) -> Result<(PathBuf, std::fs::OpenOptions), OpError> {
+) -> Result<(PathBuf, std::fs::OpenOptions), ErrBox> {
   let args: OpenArgs = serde_json::from_value(args)?;
   let path = Path::new(&args.path).to_path_buf();
 
@@ -125,7 +128,7 @@ fn op_open_sync(
   resource_table: &mut ResourceTable,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<Value, OpError> {
+) -> Result<Value, ErrBox> {
   let (path, open_options) = open_helper(state, args)?;
   let std_file = open_options.open(path)?;
   let tokio_file = tokio::fs::File::from_std(std_file);
@@ -144,7 +147,7 @@ async fn op_open_async(
   resource_table: Rc<RefCell<ResourceTable>>,
   args: Value,
   _zero_copy: BufVec,
-) -> Result<Value, OpError> {
+) -> Result<Value, ErrBox> {
   let (path, open_options) = open_helper(&state, args)?;
   let tokio_file = tokio::fs::OpenOptions::from(open_options)
     .open(path)
@@ -173,7 +176,7 @@ fn op_seek(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   use std::io::{Seek, SeekFrom};
   let args: SeekArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -185,10 +188,7 @@ fn op_seek(
     1 => SeekFrom::Current(offset),
     2 => SeekFrom::End(offset),
     _ => {
-      return Err(OpError::type_error(format!(
-        "Invalid seek mode: {}",
-        whence
-      )));
+      return Err(ErrBox::type_error(format!("Invalid seek mode: {}", whence)));
     }
   };
 
@@ -198,8 +198,8 @@ fn op_seek(
   if is_sync {
     let mut resource_table = resource_table.borrow_mut();
     let pos = std_file_resource(&mut resource_table, rid, |r| match r {
-      Ok(std_file) => std_file.seek(seek_from).map_err(OpError::from),
-      Err(_) => Err(OpError::type_error(
+      Ok(std_file) => std_file.seek(seek_from).map_err(ErrBox::from),
+      Err(_) => Err(ErrBox::type_error(
         "cannot seek on this type of resource".to_string(),
       )),
     })?;
@@ -210,8 +210,8 @@ fn op_seek(
     let fut = async move {
       let mut resource_table = resource_table.borrow_mut();
       let pos = std_file_resource(&mut resource_table, rid, |r| match r {
-        Ok(std_file) => std_file.seek(seek_from).map_err(OpError::from),
-        Err(_) => Err(OpError::type_error(
+        Ok(std_file) => std_file.seek(seek_from).map_err(ErrBox::from),
+        Err(_) => Err(ErrBox::type_error(
           "cannot seek on this type of resource".to_string(),
         )),
       })?;
@@ -233,7 +233,7 @@ fn op_fdatasync(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.fdatasync");
   let args: FdatasyncArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -244,8 +244,8 @@ fn op_fdatasync(
   if is_sync {
     let mut resource_table = resource_table.borrow_mut();
     std_file_resource(&mut resource_table, rid, |r| match r {
-      Ok(std_file) => std_file.sync_data().map_err(OpError::from),
-      Err(_) => Err(OpError::type_error(
+      Ok(std_file) => std_file.sync_data().map_err(ErrBox::from),
+      Err(_) => Err(ErrBox::type_error(
         "cannot sync this type of resource".to_string(),
       )),
     })?;
@@ -254,8 +254,8 @@ fn op_fdatasync(
     let fut = async move {
       let mut resource_table = resource_table.borrow_mut();
       std_file_resource(&mut resource_table, rid, |r| match r {
-        Ok(std_file) => std_file.sync_data().map_err(OpError::from),
-        Err(_) => Err(OpError::type_error(
+        Ok(std_file) => std_file.sync_data().map_err(ErrBox::from),
+        Err(_) => Err(ErrBox::type_error(
           "cannot sync this type of resource".to_string(),
         )),
       })?;
@@ -277,7 +277,7 @@ fn op_fsync(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.fsync");
   let args: FsyncArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -288,8 +288,8 @@ fn op_fsync(
   if is_sync {
     let mut resource_table = resource_table.borrow_mut();
     std_file_resource(&mut resource_table, rid, |r| match r {
-      Ok(std_file) => std_file.sync_all().map_err(OpError::from),
-      Err(_) => Err(OpError::type_error(
+      Ok(std_file) => std_file.sync_all().map_err(ErrBox::from),
+      Err(_) => Err(ErrBox::type_error(
         "cannot sync this type of resource".to_string(),
       )),
     })?;
@@ -298,8 +298,8 @@ fn op_fsync(
     let fut = async move {
       let mut resource_table = resource_table.borrow_mut();
       std_file_resource(&mut resource_table, rid, |r| match r {
-        Ok(std_file) => std_file.sync_all().map_err(OpError::from),
-        Err(_) => Err(OpError::type_error(
+        Ok(std_file) => std_file.sync_all().map_err(ErrBox::from),
+        Err(_) => Err(ErrBox::type_error(
           "cannot sync this type of resource".to_string(),
         )),
       })?;
@@ -321,7 +321,7 @@ fn op_fstat(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.fstat");
   let args: FstatArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -332,8 +332,8 @@ fn op_fstat(
   if is_sync {
     let mut resource_table = resource_table.borrow_mut();
     let metadata = std_file_resource(&mut resource_table, rid, |r| match r {
-      Ok(std_file) => std_file.metadata().map_err(OpError::from),
-      Err(_) => Err(OpError::type_error(
+      Ok(std_file) => std_file.metadata().map_err(ErrBox::from),
+      Err(_) => Err(ErrBox::type_error(
         "cannot stat this type of resource".to_string(),
       )),
     })?;
@@ -343,8 +343,8 @@ fn op_fstat(
       let mut resource_table = resource_table.borrow_mut();
       let metadata =
         std_file_resource(&mut resource_table, rid, |r| match r {
-          Ok(std_file) => std_file.metadata().map_err(OpError::from),
-          Err(_) => Err(OpError::type_error(
+          Ok(std_file) => std_file.metadata().map_err(ErrBox::from),
+          Err(_) => Err(ErrBox::type_error(
             "cannot stat this type of resource".to_string(),
           )),
         })?;
@@ -363,7 +363,7 @@ fn op_umask(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.umask");
   let args: UmaskArgs = serde_json::from_value(args)?;
   // TODO implement umask for Windows
@@ -372,7 +372,7 @@ fn op_umask(
   #[cfg(not(unix))]
   {
     let _ = args.mask; // avoid unused warning.
-    Err(OpError::not_implemented())
+    Err(ErrBox::not_supported())
   }
   #[cfg(unix)]
   {
@@ -401,7 +401,7 @@ fn op_chdir(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ChdirArgs = serde_json::from_value(args)?;
   let d = PathBuf::from(&args.directory);
   state.check_read(&d)?;
@@ -422,7 +422,7 @@ fn op_mkdir(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: MkdirArgs = serde_json::from_value(args)?;
   let path = Path::new(&args.path).to_path_buf();
   let mode = args.mode.unwrap_or(0o777) & 0o777;
@@ -456,7 +456,7 @@ fn op_chmod(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ChmodArgs = serde_json::from_value(args)?;
   let path = Path::new(&args.path).to_path_buf();
   let mode = args.mode & 0o777;
@@ -478,7 +478,7 @@ fn op_chmod(
     {
       // Still check file/dir exists on Windows
       let _metadata = std::fs::metadata(&path)?;
-      Err(OpError::not_implemented())
+      Err(ErrBox::not_supported())
     }
   })
 }
@@ -496,7 +496,7 @@ fn op_chown(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ChownArgs = serde_json::from_value(args)?;
   let path = Path::new(&args.path).to_path_buf();
 
@@ -515,9 +515,7 @@ fn op_chown(
     }
     // TODO Implement chown for Windows
     #[cfg(not(unix))]
-    {
-      Err(OpError::not_implemented())
-    }
+    Err(ErrBox::not_supported())
   })
 }
 
@@ -533,7 +531,7 @@ fn op_remove(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: RemoveArgs = serde_json::from_value(args)?;
   let path = PathBuf::from(&args.path);
   let recursive = args.recursive;
@@ -587,7 +585,7 @@ fn op_copy_file(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: CopyFileArgs = serde_json::from_value(args)?;
   let from = PathBuf::from(&args.from);
   let to = PathBuf::from(&args.to);
@@ -602,7 +600,7 @@ fn op_copy_file(
     // See https://github.com/rust-lang/rust/issues/54800
     // Once the issue is resolved, we should remove this workaround.
     if cfg!(unix) && !from.is_file() {
-      return Err(OpError::not_found("File not found".to_string()));
+      return Err(ErrBox::new("NotFound", "File not found"));
     }
 
     // returns size of from as u64 (we ignore)
@@ -681,7 +679,7 @@ fn op_stat(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: StatArgs = serde_json::from_value(args)?;
   let path = PathBuf::from(&args.path);
   let lstat = args.lstat;
@@ -711,7 +709,7 @@ fn op_realpath(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: RealpathArgs = serde_json::from_value(args)?;
   let path = PathBuf::from(&args.path);
 
@@ -746,7 +744,7 @@ fn op_read_dir(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ReadDirArgs = serde_json::from_value(args)?;
   let path = PathBuf::from(&args.path);
 
@@ -789,7 +787,7 @@ fn op_rename(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: RenameArgs = serde_json::from_value(args)?;
   let oldpath = PathBuf::from(&args.oldpath);
   let newpath = PathBuf::from(&args.newpath);
@@ -818,7 +816,7 @@ fn op_link(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.link");
   let args: LinkArgs = serde_json::from_value(args)?;
   let oldpath = PathBuf::from(&args.oldpath);
@@ -856,7 +854,7 @@ fn op_symlink(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.symlink");
   let args: SymlinkArgs = serde_json::from_value(args)?;
   let oldpath = PathBuf::from(&args.oldpath);
@@ -881,7 +879,7 @@ fn op_symlink(
         Some(options) => match options._type.as_ref() {
           "file" => symlink_file(&oldpath, &newpath)?,
           "dir" => symlink_dir(&oldpath, &newpath)?,
-          _ => return Err(OpError::type_error("unsupported type".to_string())),
+          _ => return Err(ErrBox::type_error("unsupported type".to_string())),
         },
         None => {
           let old_meta = std::fs::metadata(&oldpath);
@@ -893,7 +891,7 @@ fn op_symlink(
                 symlink_dir(&oldpath, &newpath)?
               }
             }
-            Err(_) => return Err(OpError::type_error(
+            Err(_) => return Err(ErrBox::type_error(
               "you must pass a `options` argument for non-existent target path in windows"
                 .to_string(),
             )),
@@ -916,7 +914,7 @@ fn op_read_link(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ReadLinkArgs = serde_json::from_value(args)?;
   let path = PathBuf::from(&args.path);
 
@@ -944,7 +942,7 @@ fn op_ftruncate(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.ftruncate");
   let args: FtruncateArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -956,8 +954,8 @@ fn op_ftruncate(
   if is_sync {
     let mut resource_table = resource_table.borrow_mut();
     std_file_resource(&mut resource_table, rid, |r| match r {
-      Ok(std_file) => std_file.set_len(len).map_err(OpError::from),
-      Err(_) => Err(OpError::type_error(
+      Ok(std_file) => std_file.set_len(len).map_err(ErrBox::from),
+      Err(_) => Err(ErrBox::type_error(
         "cannot truncate this type of resource".to_string(),
       )),
     })?;
@@ -966,8 +964,8 @@ fn op_ftruncate(
     let fut = async move {
       let mut resource_table = resource_table.borrow_mut();
       std_file_resource(&mut resource_table, rid, |r| match r {
-        Ok(std_file) => std_file.set_len(len).map_err(OpError::from),
-        Err(_) => Err(OpError::type_error(
+        Ok(std_file) => std_file.set_len(len).map_err(ErrBox::from),
+        Err(_) => Err(ErrBox::type_error(
           "cannot truncate this type of resource".to_string(),
         )),
       })?;
@@ -989,7 +987,7 @@ fn op_truncate(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: TruncateArgs = serde_json::from_value(args)?;
   let path = PathBuf::from(&args.path);
   let len = args.len;
@@ -1063,7 +1061,7 @@ fn op_make_temp_dir(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: MakeTempArgs = serde_json::from_value(args)?;
 
   let dir = args.dir.map(|s| PathBuf::from(&s));
@@ -1094,7 +1092,7 @@ fn op_make_temp_file(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: MakeTempArgs = serde_json::from_value(args)?;
 
   let dir = args.dir.map(|s| PathBuf::from(&s));
@@ -1134,7 +1132,7 @@ fn op_utime(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.utime");
 
   let args: UtimeArgs = serde_json::from_value(args)?;
@@ -1154,7 +1152,7 @@ fn op_cwd(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let path = current_dir()?;
   state.check_read_blind(&path, "CWD")?;
   let path_str = into_string(path.into_os_string())?;
diff --git a/cli/ops/fs_events.rs b/cli/ops/fs_events.rs
index fcaf138f8..e798796be 100644
--- a/cli/ops/fs_events.rs
+++ b/cli/ops/fs_events.rs
@@ -1,6 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
@@ -68,7 +67,7 @@ pub fn op_fs_events_open(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   #[derive(Deserialize)]
   struct OpenArgs {
     recursive: bool,
@@ -84,8 +83,7 @@ pub fn op_fs_events_open(
       // Ignore result, if send failed it means that watcher was already closed,
       // but not all messages have been flushed.
       let _ = sender.try_send(res2);
-    })
-    .map_err(ErrBox::from)?;
+    })?;
   let recursive_mode = if args.recursive {
     RecursiveMode::Recursive
   } else {
@@ -93,7 +91,7 @@ pub fn op_fs_events_open(
   };
   for path in &args.paths {
     state.check_read(&PathBuf::from(path))?;
-    watcher.watch(path, recursive_mode).map_err(ErrBox::from)?;
+    watcher.watch(path, recursive_mode)?;
   }
   let resource = FsEventsResource { watcher, receiver };
   let mut resource_table = isolate_state.resource_table.borrow_mut();
@@ -106,7 +104,7 @@ pub fn op_fs_events_poll(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   #[derive(Deserialize)]
   struct PollArgs {
     rid: u32,
@@ -117,13 +115,13 @@ pub fn op_fs_events_poll(
     let mut resource_table = resource_table.borrow_mut();
     let watcher = resource_table
       .get_mut::<FsEventsResource>(rid)
-      .ok_or_else(OpError::bad_resource_id)?;
+      .ok_or_else(ErrBox::bad_resource_id)?;
     watcher
       .receiver
       .poll_recv(cx)
       .map(|maybe_result| match maybe_result {
         Some(Ok(value)) => Ok(json!({ "value": value, "done": false })),
-        Some(Err(err)) => Err(OpError::from(err)),
+        Some(Err(err)) => Err(err),
         None => Ok(json!({ "done": true })),
       })
   });
diff --git a/cli/ops/idna.rs b/cli/ops/idna.rs
index c76ceba89..9585e0977 100644
--- a/cli/ops/idna.rs
+++ b/cli/ops/idna.rs
@@ -3,9 +3,9 @@
 //! https://url.spec.whatwg.org/#idna
 
 use super::dispatch_json::{Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use idna::{domain_to_ascii, domain_to_ascii_strict};
 use std::rc::Rc;
@@ -25,14 +25,16 @@ fn op_domain_to_ascii(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: DomainToAscii = serde_json::from_value(args)?;
-  let domain = if args.be_strict {
+  if args.be_strict {
     domain_to_ascii_strict(args.domain.as_str())
-      .map_err(|_| OpError::invalid_domain_error())?
   } else {
     domain_to_ascii(args.domain.as_str())
-      .map_err(|_| OpError::invalid_domain_error())?
-  };
-  Ok(JsonOp::Sync(json!(domain)))
+  }
+  .map_err(|err| {
+    let message = format!("Invalid IDNA encoded domain name: {:?}", err);
+    ErrBox::new("URIError", message)
+  })
+  .map(|domain| JsonOp::Sync(json!(domain)))
 }
diff --git a/cli/ops/io.rs b/cli/ops/io.rs
index 4d03e0ef7..6b97f542c 100644
--- a/cli/ops/io.rs
+++ b/cli/ops/io.rs
@@ -1,9 +1,9 @@
 use super::dispatch_minimal::MinimalOp;
 use crate::http_util::HttpBody;
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ResourceTable;
 use deno_core::ZeroCopyBuf;
 use futures::future::poll_fn;
@@ -116,8 +116,8 @@ fn get_stdio_stream(
   }
 }
 
-fn no_buffer_specified() -> OpError {
-  OpError::type_error("no buffer specified".to_string())
+fn no_buffer_specified() -> ErrBox {
+  ErrBox::type_error("no buffer specified".to_string())
 }
 
 #[cfg(unix)]
@@ -159,7 +159,7 @@ impl Drop for StreamResourceHolder {
 }
 
 impl StreamResourceHolder {
-  pub fn track_task(&mut self, cx: &Context) -> Result<usize, OpError> {
+  pub fn track_task(&mut self, cx: &Context) -> Result<usize, ErrBox> {
     let waker = futures::task::AtomicWaker::new();
     waker.register(cx.waker());
     // Its OK if it overflows
@@ -200,13 +200,13 @@ impl<T: AsyncRead + Unpin> UnpinAsyncRead for T {}
 impl<T: AsyncWrite + Unpin> UnpinAsyncWrite for T {}
 
 /// `DenoAsyncRead` is the same as the `tokio_io::AsyncRead` trait
-/// but uses an `OpError` error instead of `std::io:Error`
+/// but uses an `ErrBox` error instead of `std::io:Error`
 pub trait DenoAsyncRead {
   fn poll_read(
     &mut self,
     cx: &mut Context,
     buf: &mut [u8],
-  ) -> Poll<Result<usize, OpError>>;
+  ) -> Poll<Result<usize, ErrBox>>;
 }
 
 impl DenoAsyncRead for StreamResource {
@@ -214,11 +214,11 @@ impl DenoAsyncRead for StreamResource {
     &mut self,
     cx: &mut Context,
     buf: &mut [u8],
-  ) -> Poll<Result<usize, OpError>> {
+  ) -> Poll<Result<usize, ErrBox>> {
     use StreamResource::*;
     let f: &mut dyn UnpinAsyncRead = match self {
       FsFile(Some((f, _))) => f,
-      FsFile(None) => return Poll::Ready(Err(OpError::resource_unavailable())),
+      FsFile(None) => return Poll::Ready(Err(ErrBox::resource_unavailable())),
       Stdin(f, _) => f,
       TcpStream(Some(f)) => f,
       #[cfg(not(windows))]
@@ -228,7 +228,7 @@ impl DenoAsyncRead for StreamResource {
       ChildStdout(f) => f,
       ChildStderr(f) => f,
       HttpBody(f) => f,
-      _ => return Err(OpError::bad_resource_id()).into(),
+      _ => return Err(ErrBox::bad_resource_id()).into(),
     };
     let v = ready!(Pin::new(f).poll_read(cx, buf))?;
     Ok(v).into()
@@ -260,9 +260,9 @@ pub fn op_read(
           std_file
             .read(&mut zero_copy[0])
             .map(|n: usize| n as i32)
-            .map_err(OpError::from)
+            .map_err(ErrBox::from)
         }
-        Err(_) => Err(OpError::type_error(
+        Err(_) => Err(ErrBox::type_error(
           "sync read not allowed on this resource".to_string(),
         )),
       })
@@ -274,13 +274,10 @@ pub fn op_read(
         let mut resource_table = resource_table.borrow_mut();
         let resource_holder = resource_table
           .get_mut::<StreamResourceHolder>(rid as u32)
-          .ok_or_else(OpError::bad_resource_id)?;
+          .ok_or_else(ErrBox::bad_resource_id)?;
 
         let mut task_tracker_id: Option<usize> = None;
-        let nread = match resource_holder
-          .resource
-          .poll_read(cx, &mut zero_copy)
-          .map_err(OpError::from)
+        let nread = match resource_holder.resource.poll_read(cx, &mut zero_copy)
         {
           Poll::Ready(t) => {
             if let Some(id) = task_tracker_id {
@@ -301,17 +298,17 @@ pub fn op_read(
 }
 
 /// `DenoAsyncWrite` is the same as the `tokio_io::AsyncWrite` trait
-/// but uses an `OpError` error instead of `std::io:Error`
+/// but uses an `ErrBox` error instead of `std::io:Error`
 pub trait DenoAsyncWrite {
   fn poll_write(
     &mut self,
     cx: &mut Context,
     buf: &[u8],
-  ) -> Poll<Result<usize, OpError>>;
+  ) -> Poll<Result<usize, ErrBox>>;
 
-  fn poll_close(&mut self, cx: &mut Context) -> Poll<Result<(), OpError>>;
+  fn poll_close(&mut self, cx: &mut Context) -> Poll<Result<(), ErrBox>>;
 
-  fn poll_flush(&mut self, cx: &mut Context) -> Poll<Result<(), OpError>>;
+  fn poll_flush(&mut self, cx: &mut Context) -> Poll<Result<(), ErrBox>>;
 }
 
 impl DenoAsyncWrite for StreamResource {
@@ -319,7 +316,7 @@ impl DenoAsyncWrite for StreamResource {
     &mut self,
     cx: &mut Context,
     buf: &[u8],
-  ) -> Poll<Result<usize, OpError>> {
+  ) -> Poll<Result<usize, ErrBox>> {
     use StreamResource::*;
     let f: &mut dyn UnpinAsyncWrite = match self {
       FsFile(Some((f, _))) => f,
@@ -330,14 +327,14 @@ impl DenoAsyncWrite for StreamResource {
       ClientTlsStream(f) => f,
       ServerTlsStream(f) => f,
       ChildStdin(f) => f,
-      _ => return Err(OpError::bad_resource_id()).into(),
+      _ => return Err(ErrBox::bad_resource_id()).into(),
     };
 
     let v = ready!(Pin::new(f).poll_write(cx, buf))?;
     Ok(v).into()
   }
 
-  fn poll_flush(&mut self, cx: &mut Context) -> Poll<Result<(), OpError>> {
+  fn poll_flush(&mut self, cx: &mut Context) -> Poll<Result<(), ErrBox>> {
     use StreamResource::*;
     let f: &mut dyn UnpinAsyncWrite = match self {
       FsFile(Some((f, _))) => f,
@@ -348,14 +345,14 @@ impl DenoAsyncWrite for StreamResource {
       ClientTlsStream(f) => f,
       ServerTlsStream(f) => f,
       ChildStdin(f) => f,
-      _ => return Err(OpError::bad_resource_id()).into(),
+      _ => return Err(ErrBox::bad_resource_id()).into(),
     };
 
     ready!(Pin::new(f).poll_flush(cx))?;
     Ok(()).into()
   }
 
-  fn poll_close(&mut self, _cx: &mut Context) -> Poll<Result<(), OpError>> {
+  fn poll_close(&mut self, _cx: &mut Context) -> Poll<Result<(), ErrBox>> {
     unimplemented!()
   }
 }
@@ -384,9 +381,9 @@ pub fn op_write(
           std_file
             .write(&zero_copy[0])
             .map(|nwritten: usize| nwritten as i32)
-            .map_err(OpError::from)
+            .map_err(ErrBox::from)
         }
-        Err(_) => Err(OpError::type_error(
+        Err(_) => Err(ErrBox::type_error(
           "sync read not allowed on this resource".to_string(),
         )),
       })
@@ -400,7 +397,7 @@ pub fn op_write(
           let mut resource_table = resource_table.borrow_mut();
           let resource_holder = resource_table
             .get_mut::<StreamResourceHolder>(rid as u32)
-            .ok_or_else(OpError::bad_resource_id)?;
+            .ok_or_else(ErrBox::bad_resource_id)?;
           resource_holder.resource.poll_write(cx, &zero_copy)
         })
         .await?;
@@ -413,7 +410,7 @@ pub fn op_write(
           let mut resource_table = resource_table.borrow_mut();
           let resource_holder = resource_table
             .get_mut::<StreamResourceHolder>(rid as u32)
-            .ok_or_else(OpError::bad_resource_id)?;
+            .ok_or_else(ErrBox::bad_resource_id)?;
           resource_holder.resource.poll_flush(cx)
         })
         .await?;
@@ -436,11 +433,10 @@ pub fn std_file_resource<F, T>(
   resource_table: &mut ResourceTable,
   rid: u32,
   mut f: F,
-) -> Result<T, OpError>
+) -> Result<T, ErrBox>
 where
-  F: FnMut(
-    Result<&mut std::fs::File, &mut StreamResource>,
-  ) -> Result<T, OpError>,
+  F:
+    FnMut(Result<&mut std::fs::File, &mut StreamResource>) -> Result<T, ErrBox>,
 {
   // First we look up the rid in the resource table.
   let mut r = resource_table.get_mut::<StreamResourceHolder>(rid);
@@ -469,16 +465,16 @@ where
               // some operation is in-flight.
               resource_holder.resource =
                 StreamResource::FsFile(Some((tokio_file, metadata)));
-              Err(OpError::resource_unavailable())
+              Err(ErrBox::resource_unavailable())
             }
           }
         } else {
-          Err(OpError::resource_unavailable())
+          Err(ErrBox::resource_unavailable())
         }
       }
       _ => f(Err(&mut resource_holder.resource)),
     }
   } else {
-    Err(OpError::bad_resource_id())
+    Err(ErrBox::bad_resource_id())
   }
 }
diff --git a/cli/ops/net.rs b/cli/ops/net.rs
index 445c69106..25639cb79 100644
--- a/cli/ops/net.rs
+++ b/cli/ops/net.rs
@@ -1,16 +1,15 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use super::io::{StreamResource, StreamResourceHolder};
-use crate::op_error::OpError;
 use crate::resolve_addr::resolve_addr;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ResourceTable;
 use deno_core::ZeroCopyBuf;
 use futures::future::poll_fn;
 use futures::future::FutureExt;
-use std::convert::From;
 use std::net::Shutdown;
 use std::net::SocketAddr;
 use std::rc::Rc;
@@ -45,7 +44,7 @@ fn accept_tcp(
   isolate_state: &mut CoreIsolateState,
   args: AcceptArgs,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let rid = args.rid as u32;
   let resource_table = isolate_state.resource_table.clone();
 
@@ -55,10 +54,10 @@ fn accept_tcp(
       let listener_resource = resource_table
         .get_mut::<TcpListenerResource>(rid)
         .ok_or_else(|| {
-          OpError::bad_resource("Listener has been closed".to_string())
+          ErrBox::bad_resource("Listener has been closed".to_string())
         })?;
       let listener = &mut listener_resource.listener;
-      match listener.poll_accept(cx).map_err(OpError::from) {
+      match listener.poll_accept(cx).map_err(ErrBox::from) {
         Poll::Ready(Ok((stream, addr))) => {
           listener_resource.untrack_task();
           Poll::Ready(Ok((stream, addr)))
@@ -106,13 +105,13 @@ fn op_accept(
   _state: &Rc<State>,
   args: Value,
   zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: AcceptArgs = serde_json::from_value(args)?;
   match args.transport.as_str() {
     "tcp" => accept_tcp(isolate_state, args, zero_copy),
     #[cfg(unix)]
     "unix" => net_unix::accept_unix(isolate_state, args.rid as u32, zero_copy),
-    _ => Err(OpError::other(format!(
+    _ => Err(ErrBox::error(format!(
       "Unsupported transport protocol {}",
       args.transport
     ))),
@@ -130,7 +129,7 @@ fn receive_udp(
   _state: &Rc<State>,
   args: ReceiveArgs,
   zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(zero_copy.len(), 1, "Invalid number of arguments");
   let mut zero_copy = zero_copy[0].clone();
 
@@ -144,12 +143,12 @@ fn receive_udp(
       let resource = resource_table
         .get_mut::<UdpSocketResource>(rid)
         .ok_or_else(|| {
-          OpError::bad_resource("Socket has been closed".to_string())
+          ErrBox::bad_resource("Socket has been closed".to_string())
         })?;
       let socket = &mut resource.socket;
       socket
         .poll_recv_from(cx, &mut zero_copy)
-        .map_err(OpError::from)
+        .map_err(ErrBox::from)
     });
     let (size, remote_addr) = receive_fut.await?;
     Ok(json!({
@@ -170,7 +169,7 @@ fn op_datagram_receive(
   state: &Rc<State>,
   args: Value,
   zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(zero_copy.len(), 1, "Invalid number of arguments");
 
   let args: ReceiveArgs = serde_json::from_value(args)?;
@@ -180,7 +179,7 @@ fn op_datagram_receive(
     "unixpacket" => {
       net_unix::receive_unix_packet(isolate_state, args.rid as u32, zero_copy)
     }
-    _ => Err(OpError::other(format!(
+    _ => Err(ErrBox::error(format!(
       "Unsupported transport protocol {}",
       args.transport
     ))),
@@ -200,7 +199,7 @@ fn op_datagram_send(
   state: &Rc<State>,
   args: Value,
   zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(zero_copy.len(), 1, "Invalid number of arguments");
   let zero_copy = zero_copy[0].clone();
 
@@ -218,13 +217,13 @@ fn op_datagram_send(
         let resource = resource_table
           .get_mut::<UdpSocketResource>(rid as u32)
           .ok_or_else(|| {
-            OpError::bad_resource("Socket has been closed".to_string())
+            ErrBox::bad_resource("Socket has been closed".to_string())
           })?;
         resource
           .socket
           .poll_send_to(cx, &zero_copy, &addr)
-          .map_err(OpError::from)
           .map_ok(|byte_length| json!(byte_length))
+          .map_err(ErrBox::from)
       });
       Ok(JsonOp::Async(f.boxed_local()))
     }
@@ -241,9 +240,8 @@ fn op_datagram_send(
         let resource = resource_table
           .get_mut::<net_unix::UnixDatagramResource>(rid as u32)
           .ok_or_else(|| {
-            OpError::other("Socket has been closed".to_string())
+            ErrBox::new("NotConnected", "Socket has been closed")
           })?;
-
         let socket = &mut resource.socket;
         let byte_length = socket
           .send_to(&zero_copy, &resource.local_addr.as_pathname().unwrap())
@@ -254,7 +252,7 @@ fn op_datagram_send(
 
       Ok(JsonOp::Async(op.boxed_local()))
     }
-    _ => Err(OpError::other("Wrong argument format!".to_owned())),
+    _ => Err(ErrBox::type_error("Wrong argument format!")),
   }
 }
 
@@ -270,7 +268,7 @@ fn op_connect(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let resource_table = isolate_state.resource_table.clone();
   match serde_json::from_value(args)? {
     ConnectArgs {
@@ -341,7 +339,7 @@ fn op_connect(
       };
       Ok(JsonOp::Async(op.boxed_local()))
     }
-    _ => Err(OpError::other("Wrong argument format!".to_owned())),
+    _ => Err(ErrBox::type_error("Wrong argument format!")),
   }
 }
 
@@ -356,7 +354,7 @@ fn op_shutdown(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.shutdown");
 
   let args: ShutdownArgs = serde_json::from_value(args)?;
@@ -373,17 +371,16 @@ fn op_shutdown(
   let mut resource_table = isolate_state.resource_table.borrow_mut();
   let resource_holder = resource_table
     .get_mut::<StreamResourceHolder>(rid)
-    .ok_or_else(OpError::bad_resource_id)?;
+    .ok_or_else(ErrBox::bad_resource_id)?;
   match resource_holder.resource {
     StreamResource::TcpStream(Some(ref mut stream)) => {
-      TcpStream::shutdown(stream, shutdown_mode).map_err(OpError::from)?;
+      TcpStream::shutdown(stream, shutdown_mode)?;
     }
     #[cfg(unix)]
     StreamResource::UnixStream(ref mut stream) => {
-      net_unix::UnixStream::shutdown(stream, shutdown_mode)
-        .map_err(OpError::from)?;
+      net_unix::UnixStream::shutdown(stream, shutdown_mode)?;
     }
-    _ => return Err(OpError::bad_resource_id()),
+    _ => return Err(ErrBox::bad_resource_id()),
   }
 
   Ok(JsonOp::Sync(json!({})))
@@ -407,13 +404,13 @@ impl TcpListenerResource {
   /// can be notified when listener is closed.
   ///
   /// Throws an error if another task is already tracked.
-  pub fn track_task(&mut self, cx: &Context) -> Result<(), OpError> {
+  pub fn track_task(&mut self, cx: &Context) -> Result<(), ErrBox> {
     // Currently, we only allow tracking a single accept task for a listener.
     // This might be changed in the future with multiple workers.
     // Caveat: TcpListener by itself also only tracks an accept task at a time.
     // See https://github.com/tokio-rs/tokio/issues/846#issuecomment-454208883
     if self.waker.is_some() {
-      return Err(OpError::other("Another accept task is ongoing".to_string()));
+      return Err(ErrBox::new("Busy", "Another accept task is ongoing"));
     }
 
     let waker = futures::task::AtomicWaker::new();
@@ -466,7 +463,7 @@ struct ListenArgs {
 fn listen_tcp(
   resource_table: &mut ResourceTable,
   addr: SocketAddr,
-) -> Result<(u32, SocketAddr), OpError> {
+) -> Result<(u32, SocketAddr), ErrBox> {
   let std_listener = std::net::TcpListener::bind(&addr)?;
   let listener = TcpListener::from_std(std_listener)?;
   let local_addr = listener.local_addr()?;
@@ -483,7 +480,7 @@ fn listen_tcp(
 fn listen_udp(
   resource_table: &mut ResourceTable,
   addr: SocketAddr,
-) -> Result<(u32, SocketAddr), OpError> {
+) -> Result<(u32, SocketAddr), ErrBox> {
   let std_socket = std::net::UdpSocket::bind(&addr)?;
   let socket = UdpSocket::from_std(std_socket)?;
   let local_addr = socket.local_addr()?;
@@ -498,7 +495,7 @@ fn op_listen(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let mut resource_table = isolate_state.resource_table.borrow_mut();
   match serde_json::from_value(args)? {
     ListenArgs {
@@ -563,6 +560,6 @@ fn op_listen(
       })))
     }
     #[cfg(unix)]
-    _ => Err(OpError::other("Wrong argument format!".to_owned())),
+    _ => Err(ErrBox::type_error("Wrong argument format!")),
   }
 }
diff --git a/cli/ops/net_unix.rs b/cli/ops/net_unix.rs
index 0b2ceb75a..d8f6c6736 100644
--- a/cli/ops/net_unix.rs
+++ b/cli/ops/net_unix.rs
@@ -1,7 +1,7 @@
 use super::dispatch_json::{Deserialize, JsonOp};
 use super::io::{StreamResource, StreamResourceHolder};
-use crate::op_error::OpError;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ResourceTable;
 use deno_core::ZeroCopyBuf;
 use futures::future::FutureExt;
@@ -30,13 +30,13 @@ pub fn accept_unix(
   isolate_state: &mut CoreIsolateState,
   rid: u32,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let resource_table = isolate_state.resource_table.clone();
   {
     let _ = resource_table
       .borrow()
       .get::<UnixListenerResource>(rid)
-      .ok_or_else(OpError::bad_resource_id)?;
+      .ok_or_else(ErrBox::bad_resource_id)?;
   }
   let op = async move {
     let mut resource_table_ = resource_table.borrow_mut();
@@ -44,7 +44,7 @@ pub fn accept_unix(
       resource_table_
         .get_mut::<UnixListenerResource>(rid)
         .ok_or_else(|| {
-          OpError::bad_resource("Listener has been closed".to_string())
+          ErrBox::bad_resource("Listener has been closed".to_string())
         })?
     };
 
@@ -81,7 +81,7 @@ pub fn receive_unix_packet(
   isolate_state: &mut CoreIsolateState,
   rid: u32,
   zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(zero_copy.len(), 1, "Invalid number of arguments");
   let mut zero_copy = zero_copy[0].clone();
   let resource_table = isolate_state.resource_table.clone();
@@ -91,7 +91,7 @@ pub fn receive_unix_packet(
     let resource = resource_table_
       .get_mut::<UnixDatagramResource>(rid)
       .ok_or_else(|| {
-        OpError::bad_resource("Socket has been closed".to_string())
+        ErrBox::bad_resource("Socket has been closed".to_string())
       })?;
     let (size, remote_addr) = resource.socket.recv_from(&mut zero_copy).await?;
     Ok(json!({
@@ -109,7 +109,7 @@ pub fn receive_unix_packet(
 pub fn listen_unix(
   resource_table: &mut ResourceTable,
   addr: &Path,
-) -> Result<(u32, unix::net::SocketAddr), OpError> {
+) -> Result<(u32, unix::net::SocketAddr), ErrBox> {
   if addr.exists() {
     remove_file(&addr).unwrap();
   }
@@ -124,7 +124,7 @@ pub fn listen_unix(
 pub fn listen_unix_packet(
   resource_table: &mut ResourceTable,
   addr: &Path,
-) -> Result<(u32, unix::net::SocketAddr), OpError> {
+) -> Result<(u32, unix::net::SocketAddr), ErrBox> {
   if addr.exists() {
     remove_file(&addr).unwrap();
   }
diff --git a/cli/ops/os.rs b/cli/ops/os.rs
index e46aff3e6..1b961164e 100644
--- a/cli/ops/os.rs
+++ b/cli/ops/os.rs
@@ -1,8 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::collections::HashMap;
 use std::env;
@@ -25,7 +25,7 @@ fn op_exec_path(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let current_exe = env::current_exe().unwrap();
   state.check_read_blind(&current_exe, "exec_path")?;
   // Now apply URL parser to current exe to get fully resolved path, otherwise
@@ -45,7 +45,7 @@ fn op_set_env(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: SetEnv = serde_json::from_value(args)?;
   state.check_env()?;
   env::set_var(args.key, args.value);
@@ -56,7 +56,7 @@ fn op_env(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_env()?;
   let v = env::vars().collect::<HashMap<String, String>>();
   Ok(JsonOp::Sync(json!(v)))
@@ -71,7 +71,7 @@ fn op_get_env(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: GetEnv = serde_json::from_value(args)?;
   state.check_env()?;
   let r = match env::var(args.key) {
@@ -90,7 +90,7 @@ fn op_delete_env(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: DeleteEnv = serde_json::from_value(args)?;
   state.check_env()?;
   env::remove_var(args.key);
@@ -106,7 +106,7 @@ fn op_exit(
   _s: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: Exit = serde_json::from_value(args)?;
   std::process::exit(args.code)
 }
@@ -115,7 +115,7 @@ fn op_loadavg(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.loadavg");
   state.check_env()?;
   match sys_info::loadavg() {
@@ -132,7 +132,7 @@ fn op_hostname(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.hostname");
   state.check_env()?;
   let hostname = sys_info::hostname().unwrap_or_else(|_| "".to_string());
@@ -143,7 +143,7 @@ fn op_os_release(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.osRelease");
   state.check_env()?;
   let release = sys_info::os_release().unwrap_or_else(|_| "".to_string());
diff --git a/cli/ops/permissions.rs b/cli/ops/permissions.rs
index 4cb998536..6ebabfa5c 100644
--- a/cli/ops/permissions.rs
+++ b/cli/ops/permissions.rs
@@ -1,8 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::path::Path;
 use std::rc::Rc;
@@ -33,7 +33,7 @@ pub fn op_query_permission(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: PermissionArgs = serde_json::from_value(args)?;
   let permissions = state.permissions.borrow();
   let path = args.path.as_deref();
@@ -45,7 +45,12 @@ pub fn op_query_permission(
     "run" => permissions.query_run(),
     "plugin" => permissions.query_plugin(),
     "hrtime" => permissions.query_hrtime(),
-    n => return Err(OpError::other(format!("No such permission name: {}", n))),
+    n => {
+      return Err(ErrBox::new(
+        "ReferenceError",
+        format!("No such permission name: {}", n),
+      ))
+    }
   };
   Ok(JsonOp::Sync(json!({ "state": perm.to_string() })))
 }
@@ -54,7 +59,7 @@ pub fn op_revoke_permission(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: PermissionArgs = serde_json::from_value(args)?;
   let mut permissions = state.permissions.borrow_mut();
   let path = args.path.as_deref();
@@ -66,7 +71,12 @@ pub fn op_revoke_permission(
     "run" => permissions.revoke_run(),
     "plugin" => permissions.revoke_plugin(),
     "hrtime" => permissions.revoke_hrtime(),
-    n => return Err(OpError::other(format!("No such permission name: {}", n))),
+    n => {
+      return Err(ErrBox::new(
+        "ReferenceError",
+        format!("No such permission name: {}", n),
+      ))
+    }
   };
   Ok(JsonOp::Sync(json!({ "state": perm.to_string() })))
 }
@@ -75,7 +85,7 @@ pub fn op_request_permission(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: PermissionArgs = serde_json::from_value(args)?;
   let permissions = &mut state.permissions.borrow_mut();
   let path = args.path.as_deref();
@@ -87,7 +97,12 @@ pub fn op_request_permission(
     "run" => permissions.request_run(),
     "plugin" => permissions.request_plugin(),
     "hrtime" => permissions.request_hrtime(),
-    n => return Err(OpError::other(format!("No such permission name: {}", n))),
+    n => {
+      return Err(ErrBox::new(
+        "ReferenceError",
+        format!("No such permission name: {}", n),
+      ))
+    }
   };
   Ok(JsonOp::Sync(json!({ "state": perm.to_string() })))
 }
diff --git a/cli/ops/plugin.rs b/cli/ops/plugin.rs
index 3fb149404..f06105498 100644
--- a/cli/ops/plugin.rs
+++ b/cli/ops/plugin.rs
@@ -1,5 +1,4 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-use crate::op_error::OpError;
 use crate::ops::dispatch_json::Deserialize;
 use crate::ops::dispatch_json::JsonOp;
 use crate::ops::dispatch_json::Value;
@@ -8,6 +7,7 @@ use crate::state::State;
 use deno_core::plugin_api;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::Op;
 use deno_core::OpAsyncFuture;
 use deno_core::OpId;
@@ -38,7 +38,7 @@ pub fn op_open_plugin(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.openPlugin");
   let args: OpenPluginArgs = serde_json::from_value(args).unwrap();
   let filename = PathBuf::from(&args.filename);
@@ -46,9 +46,7 @@ pub fn op_open_plugin(
   state.check_plugin(&filename)?;
 
   debug!("Loading Plugin: {:#?}", filename);
-  let plugin_lib = Library::open(filename)
-    .map(Rc::new)
-    .map_err(OpError::from)?;
+  let plugin_lib = Library::open(filename).map(Rc::new)?;
   let plugin_resource = PluginResource::new(&plugin_lib);
 
   let mut resource_table = isolate_state.resource_table.borrow_mut();
diff --git a/cli/ops/process.rs b/cli/ops/process.rs
index bf733a78e..1754812a2 100644
--- a/cli/ops/process.rs
+++ b/cli/ops/process.rs
@@ -1,17 +1,15 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use super::io::{std_file_resource, StreamResource, StreamResourceHolder};
-use crate::op_error::OpError;
 use crate::signal::kill;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ResourceTable;
 use deno_core::ZeroCopyBuf;
 use futures::future::poll_fn;
 use futures::future::FutureExt;
-use futures::TryFutureExt;
-use std::convert::From;
 use std::rc::Rc;
 use tokio::process::Command;
 
@@ -27,19 +25,19 @@ pub fn init(i: &mut CoreIsolate, s: &Rc<State>) {
 fn clone_file(
   rid: u32,
   resource_table: &mut ResourceTable,
-) -> Result<std::fs::File, OpError> {
+) -> Result<std::fs::File, ErrBox> {
   std_file_resource(resource_table, rid, move |r| match r {
-    Ok(std_file) => std_file.try_clone().map_err(OpError::from),
-    Err(_) => Err(OpError::bad_resource_id()),
+    Ok(std_file) => std_file.try_clone().map_err(ErrBox::from),
+    Err(_) => Err(ErrBox::bad_resource_id()),
   })
 }
 
-fn subprocess_stdio_map(s: &str) -> Result<std::process::Stdio, OpError> {
+fn subprocess_stdio_map(s: &str) -> Result<std::process::Stdio, ErrBox> {
   match s {
     "inherit" => Ok(std::process::Stdio::inherit()),
     "piped" => Ok(std::process::Stdio::piped()),
     "null" => Ok(std::process::Stdio::null()),
-    _ => Err(OpError::other("Invalid resource for stdio".to_string())),
+    _ => Err(ErrBox::type_error("Invalid resource for stdio")),
   }
 }
 
@@ -66,7 +64,7 @@ fn op_run(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let run_args: RunArgs = serde_json::from_value(args)?;
 
   state.check_run()?;
@@ -177,7 +175,7 @@ fn op_run_status(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: RunStatusArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
 
@@ -189,9 +187,9 @@ fn op_run_status(
       let mut resource_table = resource_table.borrow_mut();
       let child_resource = resource_table
         .get_mut::<ChildResource>(rid)
-        .ok_or_else(OpError::bad_resource_id)?;
+        .ok_or_else(ErrBox::bad_resource_id)?;
       let child = &mut child_resource.child;
-      child.map_err(OpError::from).poll_unpin(cx)
+      child.poll_unpin(cx).map_err(ErrBox::from)
     })
     .await?;
 
@@ -227,7 +225,7 @@ fn op_kill(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.kill");
   state.check_run()?;
 
diff --git a/cli/ops/random.rs b/cli/ops/random.rs
index 275f264f9..3ff5ad49f 100644
--- a/cli/ops/random.rs
+++ b/cli/ops/random.rs
@@ -1,8 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use rand::thread_rng;
 use rand::Rng;
@@ -19,7 +19,7 @@ fn op_get_random_values(
   state: &Rc<State>,
   _args: Value,
   zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(zero_copy.len(), 1);
 
   if let Some(seeded_rng) = &state.seeded_rng {
diff --git a/cli/ops/repl.rs b/cli/ops/repl.rs
index 88b7de881..b051dd574 100644
--- a/cli/ops/repl.rs
+++ b/cli/ops/repl.rs
@@ -1,11 +1,11 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{blocking_json, Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::repl;
 use crate::repl::Repl;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::rc::Rc;
 use std::sync::Arc;
@@ -29,7 +29,7 @@ fn op_repl_start(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ReplStartArgs = serde_json::from_value(args)?;
   debug!("op_repl_start {}", args.history_file);
   let history_path =
@@ -52,7 +52,7 @@ fn op_repl_readline(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ReplReadlineArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
   let prompt = args.prompt;
@@ -60,7 +60,7 @@ fn op_repl_readline(
   let resource_table = isolate_state.resource_table.borrow();
   let resource = resource_table
     .get::<ReplResource>(rid)
-    .ok_or_else(OpError::bad_resource_id)?;
+    .ok_or_else(ErrBox::bad_resource_id)?;
   let repl = resource.0.clone();
 
   blocking_json(false, move || {
diff --git a/cli/ops/resources.rs b/cli/ops/resources.rs
index a24b3b382..fb3c1bc79 100644
--- a/cli/ops/resources.rs
+++ b/cli/ops/resources.rs
@@ -1,9 +1,9 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::rc::Rc;
 
@@ -17,7 +17,7 @@ fn op_resources(
   _state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let serialized_resources = isolate_state.resource_table.borrow().entries();
   Ok(JsonOp::Sync(json!(serialized_resources)))
 }
@@ -28,7 +28,7 @@ fn op_close(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   #[derive(Deserialize)]
   struct CloseArgs {
     rid: i32,
@@ -37,6 +37,6 @@ fn op_close(
   let mut resource_table = isolate_state.resource_table.borrow_mut();
   resource_table
     .close(args.rid as u32)
-    .ok_or_else(OpError::bad_resource_id)?;
+    .ok_or_else(ErrBox::bad_resource_id)?;
   Ok(JsonOp::Sync(json!({})))
 }
diff --git a/cli/ops/runtime.rs b/cli/ops/runtime.rs
index b4fb3c496..26e1b2a33 100644
--- a/cli/ops/runtime.rs
+++ b/cli/ops/runtime.rs
@@ -1,11 +1,11 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{JsonOp, Value};
 use crate::colors;
-use crate::op_error::OpError;
 use crate::state::State;
 use crate::version;
 use crate::DenoSubcommand;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ModuleSpecifier;
 use deno_core::ZeroCopyBuf;
 use std::env;
@@ -21,7 +21,7 @@ fn op_start(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let gs = &state.global_state;
 
   Ok(JsonOp::Sync(json!({
@@ -46,7 +46,7 @@ fn op_main_module(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let main = &state.main_module.to_string();
   let main_url = ModuleSpecifier::resolve_url_or_path(&main)?;
   if main_url.as_url().scheme() == "file" {
@@ -60,7 +60,7 @@ fn op_metrics(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let m = &state.metrics.borrow();
 
   Ok(JsonOp::Sync(json!({
diff --git a/cli/ops/runtime_compiler.rs b/cli/ops/runtime_compiler.rs
index d77ab8f08..3aaaf019d 100644
--- a/cli/ops/runtime_compiler.rs
+++ b/cli/ops/runtime_compiler.rs
@@ -1,12 +1,12 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use crate::futures::FutureExt;
-use crate::op_error::OpError;
 use crate::state::State;
 use crate::tsc::runtime_bundle;
 use crate::tsc::runtime_compile;
 use crate::tsc::runtime_transpile;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::collections::HashMap;
 use std::rc::Rc;
@@ -29,7 +29,7 @@ fn op_compile(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.compile");
   let args: CompileArgs = serde_json::from_value(args)?;
   let global_state = state.global_state.clone();
@@ -71,7 +71,7 @@ fn op_transpile(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.transpile");
   let args: TranspileArgs = serde_json::from_value(args)?;
   let global_state = state.global_state.clone();
diff --git a/cli/ops/signal.rs b/cli/ops/signal.rs
index cb83427c8..3868c6e17 100644
--- a/cli/ops/signal.rs
+++ b/cli/ops/signal.rs
@@ -1,15 +1,16 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use std::rc::Rc;
 
 #[cfg(unix)]
 use super::dispatch_json::Deserialize;
 #[cfg(unix)]
+#[cfg(unix)]
 use futures::future::{poll_fn, FutureExt};
 #[cfg(unix)]
 use std::task::Waker;
@@ -45,7 +46,7 @@ fn op_signal_bind(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.signal");
   let args: BindSignalArgs = serde_json::from_value(args)?;
   let mut resource_table = isolate_state.resource_table.borrow_mut();
@@ -67,7 +68,7 @@ fn op_signal_poll(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.signal");
   let args: SignalArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -94,7 +95,7 @@ pub fn op_signal_unbind(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.signal");
   let args: SignalArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -109,7 +110,7 @@ pub fn op_signal_unbind(
   }
   resource_table
     .close(rid)
-    .ok_or_else(OpError::bad_resource_id)?;
+    .ok_or_else(ErrBox::bad_resource_id)?;
   Ok(JsonOp::Sync(json!({})))
 }
 
@@ -119,7 +120,7 @@ pub fn op_signal_bind(
   _state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   unimplemented!();
 }
 
@@ -129,7 +130,7 @@ fn op_signal_unbind(
   _state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   unimplemented!();
 }
 
@@ -139,6 +140,6 @@ fn op_signal_poll(
   _state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   unimplemented!();
 }
diff --git a/cli/ops/timers.rs b/cli/ops/timers.rs
index e3fe14c2c..379bacf98 100644
--- a/cli/ops/timers.rs
+++ b/cli/ops/timers.rs
@@ -1,8 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use futures::future::FutureExt;
 use std::rc::Rc;
@@ -22,7 +22,7 @@ fn op_global_timer_stop(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.global_timer.borrow_mut().cancel();
   Ok(JsonOp::Sync(json!({})))
 }
@@ -36,7 +36,7 @@ fn op_global_timer(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: GlobalTimerArgs = serde_json::from_value(args)?;
   let val = args.timeout;
 
@@ -58,7 +58,7 @@ fn op_now(
   state: &Rc<State>,
   _args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let seconds = state.start_time.elapsed().as_secs();
   let mut subsec_nanos = state.start_time.elapsed().subsec_nanos();
   let reduced_time_precision = 2_000_000; // 2ms in nanoseconds
@@ -66,12 +66,8 @@ fn op_now(
   // If the permission is not enabled
   // Round the nano result on 2 milliseconds
   // see: https://developer.mozilla.org/en-US/docs/Web/API/DOMHighResTimeStamp#Reduced_time_precision
-  if let Err(op_error) = state.check_hrtime() {
-    if op_error.kind_str == "PermissionDenied" {
-      subsec_nanos -= subsec_nanos % reduced_time_precision;
-    } else {
-      return Err(op_error);
-    }
+  if state.check_hrtime().is_err() {
+    subsec_nanos -= subsec_nanos % reduced_time_precision;
   }
 
   Ok(JsonOp::Sync(json!({
diff --git a/cli/ops/tls.rs b/cli/ops/tls.rs
index 76962f5c8..97dca9d90 100644
--- a/cli/ops/tls.rs
+++ b/cli/ops/tls.rs
@@ -1,11 +1,11 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use super::io::{StreamResource, StreamResourceHolder};
-use crate::op_error::OpError;
 use crate::resolve_addr::resolve_addr;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use futures::future::poll_fn;
 use futures::future::FutureExt;
@@ -59,7 +59,7 @@ pub fn op_start_tls(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.startTls");
   let args: StartTLSArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
@@ -81,7 +81,7 @@ pub fn op_start_tls(
       let mut resource_table_ = resource_table.borrow_mut();
       match resource_table_.remove::<StreamResourceHolder>(rid) {
         Some(resource) => *resource,
-        None => return Err(OpError::bad_resource_id()),
+        None => return Err(ErrBox::bad_resource_id()),
       }
     };
 
@@ -127,7 +127,7 @@ pub fn op_start_tls(
           }
       }))
     } else {
-      Err(OpError::bad_resource_id())
+      Err(ErrBox::bad_resource_id())
     }
   };
   Ok(JsonOp::Async(op.boxed_local()))
@@ -138,7 +138,7 @@ pub fn op_connect_tls(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ConnectTLSArgs = serde_json::from_value(args)?;
   let cert_file = args.cert_file.clone();
   let resource_table = isolate_state.resource_table.clone();
@@ -195,31 +195,31 @@ pub fn op_connect_tls(
   Ok(JsonOp::Async(op.boxed_local()))
 }
 
-fn load_certs(path: &str) -> Result<Vec<Certificate>, OpError> {
+fn load_certs(path: &str) -> Result<Vec<Certificate>, ErrBox> {
   let cert_file = File::open(path)?;
   let reader = &mut BufReader::new(cert_file);
 
   let certs = certs(reader)
-    .map_err(|_| OpError::other("Unable to decode certificate".to_string()))?;
+    .map_err(|_| ErrBox::new("InvalidData", "Unable to decode certificate"))?;
 
   if certs.is_empty() {
-    let e = OpError::other("No certificates found in cert file".to_string());
+    let e = ErrBox::new("InvalidData", "No certificates found in cert file");
     return Err(e);
   }
 
   Ok(certs)
 }
 
-fn key_decode_err() -> OpError {
-  OpError::other("Unable to decode key".to_string())
+fn key_decode_err() -> ErrBox {
+  ErrBox::new("InvalidData", "Unable to decode key")
 }
 
-fn key_not_found_err() -> OpError {
-  OpError::other("No keys found in key file".to_string())
+fn key_not_found_err() -> ErrBox {
+  ErrBox::new("InvalidData", "No keys found in key file")
 }
 
 /// Starts with -----BEGIN RSA PRIVATE KEY-----
-fn load_rsa_keys(path: &str) -> Result<Vec<PrivateKey>, OpError> {
+fn load_rsa_keys(path: &str) -> Result<Vec<PrivateKey>, ErrBox> {
   let key_file = File::open(path)?;
   let reader = &mut BufReader::new(key_file);
   let keys = rsa_private_keys(reader).map_err(|_| key_decode_err())?;
@@ -227,14 +227,14 @@ fn load_rsa_keys(path: &str) -> Result<Vec<PrivateKey>, OpError> {
 }
 
 /// Starts with -----BEGIN PRIVATE KEY-----
-fn load_pkcs8_keys(path: &str) -> Result<Vec<PrivateKey>, OpError> {
+fn load_pkcs8_keys(path: &str) -> Result<Vec<PrivateKey>, ErrBox> {
   let key_file = File::open(path)?;
   let reader = &mut BufReader::new(key_file);
   let keys = pkcs8_private_keys(reader).map_err(|_| key_decode_err())?;
   Ok(keys)
 }
 
-fn load_keys(path: &str) -> Result<Vec<PrivateKey>, OpError> {
+fn load_keys(path: &str) -> Result<Vec<PrivateKey>, ErrBox> {
   let path = path.to_string();
   let mut keys = load_rsa_keys(&path)?;
 
@@ -268,13 +268,13 @@ impl TlsListenerResource {
   /// can be notified when listener is closed.
   ///
   /// Throws an error if another task is already tracked.
-  pub fn track_task(&mut self, cx: &Context) -> Result<(), OpError> {
+  pub fn track_task(&mut self, cx: &Context) -> Result<(), ErrBox> {
     // Currently, we only allow tracking a single accept task for a listener.
     // This might be changed in the future with multiple workers.
     // Caveat: TcpListener by itself also only tracks an accept task at a time.
     // See https://github.com/tokio-rs/tokio/issues/846#issuecomment-454208883
     if self.waker.is_some() {
-      return Err(OpError::other("Another accept task is ongoing".to_string()));
+      return Err(ErrBox::new("Busy", "Another accept task is ongoing"));
     }
 
     let waker = futures::task::AtomicWaker::new();
@@ -312,7 +312,7 @@ fn op_listen_tls(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: ListenTlsArgs = serde_json::from_value(args)?;
   assert_eq!(args.transport, "tcp");
 
@@ -362,7 +362,7 @@ fn op_accept_tls(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: AcceptTlsArgs = serde_json::from_value(args)?;
   let rid = args.rid as u32;
   let resource_table = isolate_state.resource_table.clone();
@@ -372,10 +372,10 @@ fn op_accept_tls(
       let listener_resource = resource_table
         .get_mut::<TlsListenerResource>(rid)
         .ok_or_else(|| {
-          OpError::bad_resource("Listener has been closed".to_string())
+          ErrBox::bad_resource("Listener has been closed".to_string())
         })?;
       let listener = &mut listener_resource.listener;
-      match listener.poll_accept(cx).map_err(OpError::from) {
+      match listener.poll_accept(cx).map_err(ErrBox::from) {
         Poll::Ready(Ok((stream, addr))) => {
           listener_resource.untrack_task();
           Poll::Ready(Ok((stream, addr)))
@@ -397,7 +397,7 @@ fn op_accept_tls(
       let resource_table = resource_table.borrow();
       let resource = resource_table
         .get::<TlsListenerResource>(rid)
-        .ok_or_else(OpError::bad_resource_id)
+        .ok_or_else(ErrBox::bad_resource_id)
         .expect("Can't find tls listener");
       resource.tls_acceptor.clone()
     };
diff --git a/cli/ops/tty.rs b/cli/ops/tty.rs
index d6aaeb785..b62b727c3 100644
--- a/cli/ops/tty.rs
+++ b/cli/ops/tty.rs
@@ -1,10 +1,10 @@
 use super::dispatch_json::JsonOp;
 use super::io::std_file_resource;
 use super::io::{StreamResource, StreamResourceHolder};
-use crate::op_error::OpError;
 use crate::state::State;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 #[cfg(unix)]
 use nix::sys::termios;
@@ -23,15 +23,15 @@ const RAW_MODE_MASK: DWORD = wincon::ENABLE_LINE_INPUT
 #[cfg(windows)]
 fn get_windows_handle(
   f: &std::fs::File,
-) -> Result<std::os::windows::io::RawHandle, OpError> {
+) -> Result<std::os::windows::io::RawHandle, ErrBox> {
   use std::os::windows::io::AsRawHandle;
   use winapi::um::handleapi;
 
   let handle = f.as_raw_handle();
   if handle == handleapi::INVALID_HANDLE_VALUE {
-    return Err(OpError::from(std::io::Error::last_os_error()));
+    return Err(ErrBox::last_os_error());
   } else if handle.is_null() {
-    return Err(OpError::other("null handle".to_owned()));
+    return Err(ErrBox::new("ReferenceError", "null handle"));
   }
   Ok(handle)
 }
@@ -53,7 +53,7 @@ pub fn op_set_raw(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.setRaw");
   let args: SetRawArgs = serde_json::from_value(args)?;
   let rid = args.rid;
@@ -73,7 +73,7 @@ pub fn op_set_raw(
     let mut resource_table = isolate_state.resource_table.borrow_mut();
     let resource_holder = resource_table.get_mut::<StreamResourceHolder>(rid);
     if resource_holder.is_none() {
-      return Err(OpError::bad_resource_id());
+      return Err(ErrBox::bad_resource_id());
     }
     let resource_holder = resource_holder.unwrap();
 
@@ -98,28 +98,28 @@ pub fn op_set_raw(
               // some operation is in-flight.
               resource_holder.resource =
                 StreamResource::FsFile(Some((tokio_file, metadata)));
-              return Err(OpError::resource_unavailable());
+              return Err(ErrBox::resource_unavailable());
             }
           }
         } else {
-          return Err(OpError::resource_unavailable());
+          return Err(ErrBox::resource_unavailable());
         }
       }
       _ => {
-        return Err(OpError::bad_resource_id());
+        return Err(ErrBox::bad_resource_id());
       }
     };
 
     if handle == handleapi::INVALID_HANDLE_VALUE {
-      return Err(OpError::from(std::io::Error::last_os_error()));
+      return Err(ErrBox::last_os_error());
     } else if handle.is_null() {
-      return Err(OpError::other("null handle".to_owned()));
+      return Err(ErrBox::new("ReferenceError", "null handle"));
     }
     let mut original_mode: DWORD = 0;
     if unsafe { consoleapi::GetConsoleMode(handle, &mut original_mode) }
       == FALSE
     {
-      return Err(OpError::from(std::io::Error::last_os_error()));
+      return Err(ErrBox::last_os_error());
     }
     let new_mode = if is_raw {
       original_mode & !RAW_MODE_MASK
@@ -127,7 +127,7 @@ pub fn op_set_raw(
       original_mode | RAW_MODE_MASK
     };
     if unsafe { consoleapi::SetConsoleMode(handle, new_mode) } == FALSE {
-      return Err(OpError::from(std::io::Error::last_os_error()));
+      return Err(ErrBox::last_os_error());
     }
 
     Ok(JsonOp::Sync(json!({})))
@@ -139,7 +139,7 @@ pub fn op_set_raw(
     let mut resource_table = isolate_state.resource_table.borrow_mut();
     let resource_holder = resource_table.get_mut::<StreamResourceHolder>(rid);
     if resource_holder.is_none() {
-      return Err(OpError::bad_resource_id());
+      return Err(ErrBox::bad_resource_id());
     }
 
     if is_raw {
@@ -152,10 +152,10 @@ pub fn op_set_raw(
             (f.as_raw_fd(), &mut metadata.tty.mode)
           }
           StreamResource::FsFile(None) => {
-            return Err(OpError::resource_unavailable())
+            return Err(ErrBox::resource_unavailable())
           }
           _ => {
-            return Err(OpError::other("Not supported".to_owned()));
+            return Err(ErrBox::not_supported());
           }
         };
 
@@ -196,10 +196,10 @@ pub fn op_set_raw(
             (f.as_raw_fd(), &mut metadata.tty.mode)
           }
           StreamResource::FsFile(None) => {
-            return Err(OpError::resource_unavailable());
+            return Err(ErrBox::resource_unavailable());
           }
           _ => {
-            return Err(OpError::bad_resource_id());
+            return Err(ErrBox::bad_resource_id());
           }
         };
 
@@ -222,7 +222,7 @@ pub fn op_isatty(
   _state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: IsattyArgs = serde_json::from_value(args)?;
   let rid = args.rid;
 
@@ -269,7 +269,7 @@ pub fn op_console_size(
   state: &Rc<State>,
   args: Value,
   _zero_copy: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   state.check_unstable("Deno.consoleSize");
   let args: ConsoleSizeArgs = serde_json::from_value(args)?;
   let rid = args.rid;
@@ -292,10 +292,7 @@ pub fn op_console_size(
               &mut bufinfo,
             ) == 0
             {
-              // TODO (caspervonb) use GetLastError
-              return Err(OpError::other(
-                winapi::um::errhandlingapi::GetLastError().to_string(),
-              ));
+              return Err(ErrBox::last_os_error());
             }
 
             Ok(ConsoleSize {
@@ -313,7 +310,7 @@ pub fn op_console_size(
           unsafe {
             let mut size: libc::winsize = std::mem::zeroed();
             if libc::ioctl(fd, libc::TIOCGWINSZ, &mut size as *mut _) != 0 {
-              return Err(OpError::from(std::io::Error::last_os_error()));
+              return Err(ErrBox::last_os_error());
             }
 
             // TODO (caspervonb) return a tuple instead
@@ -324,7 +321,7 @@ pub fn op_console_size(
           }
         }
       }
-      Err(_) => Err(OpError::bad_resource_id()),
+      Err(_) => Err(ErrBox::bad_resource_id()),
     })?;
 
   Ok(JsonOp::Sync(json!(size)))
diff --git a/cli/ops/web_worker.rs b/cli/ops/web_worker.rs
index 8ad497d5c..023a4708c 100644
--- a/cli/ops/web_worker.rs
+++ b/cli/ops/web_worker.rs
@@ -1,12 +1,12 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use super::dispatch_json::{JsonOp, Value};
-use crate::op_error::OpError;
 use crate::ops::json_op;
 use crate::state::State;
 use crate::web_worker::WebWorkerHandle;
 use crate::worker::WorkerEvent;
 use deno_core::CoreIsolate;
 use deno_core::CoreIsolateState;
+use deno_core::ErrBox;
 use deno_core::ZeroCopyBuf;
 use futures::channel::mpsc;
 use std::convert::From;
@@ -19,18 +19,18 @@ pub fn web_worker_op<D>(
   &mut CoreIsolateState,
   Value,
   &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError>
+) -> Result<JsonOp, ErrBox>
 where
   D: Fn(
     &mpsc::Sender<WorkerEvent>,
     Value,
     &mut [ZeroCopyBuf],
-  ) -> Result<JsonOp, OpError>,
+  ) -> Result<JsonOp, ErrBox>,
 {
   move |_isolate_state: &mut CoreIsolateState,
         args: Value,
         zero_copy: &mut [ZeroCopyBuf]|
-        -> Result<JsonOp, OpError> { dispatcher(&sender, args, zero_copy) }
+        -> Result<JsonOp, ErrBox> { dispatcher(&sender, args, zero_copy) }
 }
 
 pub fn web_worker_op2<D>(
@@ -41,19 +41,19 @@ pub fn web_worker_op2<D>(
   &mut CoreIsolateState,
   Value,
   &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError>
+) -> Result<JsonOp, ErrBox>
 where
   D: Fn(
     WebWorkerHandle,
     &mpsc::Sender<WorkerEvent>,
     Value,
     &mut [ZeroCopyBuf],
-  ) -> Result<JsonOp, OpError>,
+  ) -> Result<JsonOp, ErrBox>,
 {
   move |_isolate_state: &mut CoreIsolateState,
         args: Value,
         zero_copy: &mut [ZeroCopyBuf]|
-        -> Result<JsonOp, OpError> {
+        -> Result<JsonOp, ErrBox> {
     dispatcher(handle.clone(), &sender, args, zero_copy)
   }
 }
@@ -86,7 +86,7 @@ fn op_worker_post_message(
   sender: &mpsc::Sender<WorkerEvent>,
   _args: Value,
   data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(data.len(), 1, "Invalid number of arguments");
   let d = Vec::from(&*data[0]).into_boxed_slice();
   let mut sender = sender.clone();
@@ -102,7 +102,7 @@ fn op_worker_close(
   sender: &mpsc::Sender<WorkerEvent>,
   _args: Value,
   _data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let mut sender = sender.clone();
   // Notify parent that we're finished
   sender.close_channel();
diff --git a/cli/ops/worker_host.rs b/cli/ops/worker_host.rs
index 47ebd9c7f..4cd55fef1 100644
--- a/cli/ops/worker_host.rs
+++ b/cli/ops/worker_host.rs
@@ -2,7 +2,6 @@
 use super::dispatch_json::{Deserialize, JsonOp, Value};
 use crate::fmt_errors::JSError;
 use crate::global_state::GlobalState;
-use crate::op_error::OpError;
 use crate::ops::io::get_stdio;
 use crate::permissions::Permissions;
 use crate::startup_data;
@@ -184,7 +183,7 @@ fn op_create_worker(
   state: &Rc<State>,
   args: Value,
   _data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: CreateWorkerArgs = serde_json::from_value(args)?;
 
   let specifier = args.specifier.clone();
@@ -215,8 +214,7 @@ fn op_create_worker(
     module_specifier,
     use_deno_namespace,
     maybe_source_code,
-  )
-  .map_err(|e| OpError::other(e.to_string()))?;
+  )?;
   // At this point all interactions with worker happen using thread
   // safe handler returned from previous function call
   parent_state
@@ -236,7 +234,7 @@ fn op_host_terminate_worker(
   state: &Rc<State>,
   args: Value,
   _data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: WorkerArgs = serde_json::from_value(args)?;
   let id = args.id as u32;
   let (join_handle, worker_handle) = state
@@ -304,7 +302,7 @@ fn op_host_get_message(
   state: &Rc<State>,
   args: Value,
   _data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   let args: WorkerArgs = serde_json::from_value(args)?;
   let id = args.id as u32;
   let state = state.clone();
@@ -345,7 +343,7 @@ fn op_host_post_message(
   state: &Rc<State>,
   args: Value,
   data: &mut [ZeroCopyBuf],
-) -> Result<JsonOp, OpError> {
+) -> Result<JsonOp, ErrBox> {
   assert_eq!(data.len(), 1, "Invalid number of arguments");
   let args: WorkerArgs = serde_json::from_value(args)?;
   let id = args.id as u32;
@@ -354,8 +352,6 @@ fn op_host_post_message(
   debug!("post message to worker {}", id);
   let workers = state.workers.borrow();
   let worker_handle = workers[&id].1.clone();
-  worker_handle
-    .post_message(msg)
-    .map_err(|e| OpError::other(e.to_string()))?;
+  worker_handle.post_message(msg)?;
   Ok(JsonOp::Sync(json!({})))
 }
diff --git a/cli/permissions.rs b/cli/permissions.rs
index 7d9fa1d45..577ebd40e 100644
--- a/cli/permissions.rs
+++ b/cli/permissions.rs
@@ -2,7 +2,7 @@
 use crate::colors;
 use crate::flags::Flags;
 use crate::fs::resolve_from_cwd;
-use crate::op_error::OpError;
+use deno_core::ErrBox;
 use serde::Deserialize;
 use std::collections::HashSet;
 use std::env::current_dir;
@@ -31,21 +31,21 @@ pub enum PermissionState {
 
 impl PermissionState {
   /// Check the permission state.
-  fn check(self, msg: &str, flag_name: &str) -> Result<(), OpError> {
+  fn check(self, msg: &str, flag_name: &str) -> Result<(), ErrBox> {
     if self == PermissionState::Granted {
       log_perm_access(msg);
       return Ok(());
     }
-    let m = format!("{}, run again with the {} flag", msg, flag_name);
-    Err(OpError::permission_denied(m))
+    let message = format!("{}, run again with the {} flag", msg, flag_name);
+    Err(ErrBox::new("PermissionDenied", message))
   }
 
   /// Check that the permissions represented by `other` don't escalate ours.
-  fn check_fork(self, other: &Self) -> Result<(), OpError> {
+  fn check_fork(self, other: &Self) -> Result<(), ErrBox> {
     if self == PermissionState::Denied && other != &PermissionState::Denied
       || self == PermissionState::Prompt && other == &PermissionState::Granted
     {
-      return Err(OpError::permission_escalation_error());
+      return Err(permission_escalation_error());
     }
     Ok(())
   }
@@ -97,13 +97,13 @@ pub struct UnaryPermission<T: Eq + Hash> {
 
 impl<T: Eq + Hash> UnaryPermission<T> {
   /// Check that the permissions represented by `other` don't escalate ours.
-  fn check_fork(&self, other: &Self) -> Result<(), OpError> {
+  fn check_fork(&self, other: &Self) -> Result<(), ErrBox> {
     self.global_state.check_fork(&other.global_state)?;
     if !self.granted_list.is_superset(&other.granted_list) {
-      return Err(OpError::permission_escalation_error());
+      return Err(permission_escalation_error());
     }
     if !self.denied_list.is_subset(&other.denied_list) {
-      return Err(OpError::permission_escalation_error());
+      return Err(permission_escalation_error());
     }
     Ok(())
   }
@@ -250,19 +250,19 @@ impl Permissions {
   pub fn query_net_url(
     &self,
     url: &Option<&str>,
-  ) -> Result<PermissionState, OpError> {
+  ) -> Result<PermissionState, ErrBox> {
     if url.is_none() {
       return Ok(self.net.global_state);
     }
     let url: &str = url.unwrap();
     // If url is invalid, then throw a TypeError.
-    let parsed = Url::parse(url).map_err(OpError::from)?;
+    let parsed = Url::parse(url)?;
     // The url may be parsed correctly but still lack a host, i.e. "localhost:235" or "mailto:someone@somewhere.com" or "file:/1.txt"
     // Note that host:port combos are parsed as scheme:path
     if parsed.host().is_none() {
-      return Err(OpError::uri_error(
-        "invalid url, expected format: <scheme>://<host>[:port][/subpath]"
-          .to_owned(),
+      return Err(ErrBox::new(
+        "URIError",
+        "invalid urlormat: <scheme>://<host>[:port][/subpath]",
       ));
     }
     Ok(self.query_net(
@@ -374,7 +374,7 @@ impl Permissions {
   pub fn request_net(
     &mut self,
     url: &Option<&str>,
-  ) -> Result<PermissionState, OpError> {
+  ) -> Result<PermissionState, ErrBox> {
     if let Some(url) = url {
       let state = self.query_net_url(&Some(url))?;
       if state == PermissionState::Prompt {
@@ -486,7 +486,7 @@ impl Permissions {
   pub fn revoke_net(
     &mut self,
     url: &Option<&str>,
-  ) -> Result<PermissionState, OpError> {
+  ) -> Result<PermissionState, ErrBox> {
     if let Some(url) = url {
       self.net.granted_list.remove(*url);
     } else {
@@ -526,7 +526,7 @@ impl Permissions {
     self.hrtime
   }
 
-  pub fn check_read(&self, path: &Path) -> Result<(), OpError> {
+  pub fn check_read(&self, path: &Path) -> Result<(), ErrBox> {
     let (resolved_path, display_path) = self.resolved_and_display_path(path);
     self.query_read(&Some(&resolved_path)).check(
       &format!("read access to \"{}\"", display_path.display()),
@@ -540,14 +540,14 @@ impl Permissions {
     &self,
     path: &Path,
     display: &str,
-  ) -> Result<(), OpError> {
+  ) -> Result<(), ErrBox> {
     let resolved_path = resolve_from_cwd(path).unwrap();
     self
       .query_read(&Some(&resolved_path))
       .check(&format!("read access to <{}>", display), "--allow-read")
   }
 
-  pub fn check_write(&self, path: &Path) -> Result<(), OpError> {
+  pub fn check_write(&self, path: &Path) -> Result<(), ErrBox> {
     let (resolved_path, display_path) = self.resolved_and_display_path(path);
     self.query_write(&Some(&resolved_path)).check(
       &format!("write access to \"{}\"", display_path.display()),
@@ -555,33 +555,33 @@ impl Permissions {
     )
   }
 
-  pub fn check_net(&self, hostname: &str, port: u16) -> Result<(), OpError> {
+  pub fn check_net(&self, hostname: &str, port: u16) -> Result<(), ErrBox> {
     self.query_net(hostname, Some(port)).check(
       &format!("network access to \"{}:{}\"", hostname, port),
       "--allow-net",
     )
   }
 
-  pub fn check_net_url(&self, url: &url::Url) -> Result<(), OpError> {
+  pub fn check_net_url(&self, url: &url::Url) -> Result<(), ErrBox> {
     let host = url
       .host_str()
-      .ok_or_else(|| OpError::uri_error("missing host".to_owned()))?;
+      .ok_or_else(|| ErrBox::new("URIError", "missing host"))?;
     self
       .query_net(host, url.port_or_known_default())
       .check(&format!("network access to \"{}\"", url), "--allow-net")
   }
 
-  pub fn check_env(&self) -> Result<(), OpError> {
+  pub fn check_env(&self) -> Result<(), ErrBox> {
     self
       .env
       .check("access to environment variables", "--allow-env")
   }
 
-  pub fn check_run(&self) -> Result<(), OpError> {
+  pub fn check_run(&self) -> Result<(), ErrBox> {
     self.run.check("access to run a subprocess", "--allow-run")
   }
 
-  pub fn check_plugin(&self, path: &Path) -> Result<(), OpError> {
+  pub fn check_plugin(&self, path: &Path) -> Result<(), ErrBox> {
     let (_, display_path) = self.resolved_and_display_path(path);
     self.plugin.check(
       &format!("access to open a plugin: {}", display_path.display()),
@@ -589,7 +589,7 @@ impl Permissions {
     )
   }
 
-  pub fn check_hrtime(&self) -> Result<(), OpError> {
+  pub fn check_hrtime(&self) -> Result<(), ErrBox> {
     self
       .hrtime
       .check("access to high precision time", "--allow-run")
@@ -605,7 +605,7 @@ impl Permissions {
     run: PermissionState,
     plugin: PermissionState,
     hrtime: PermissionState,
-  ) -> Result<Permissions, OpError> {
+  ) -> Result<Permissions, ErrBox> {
     self.read.check_fork(&read)?;
     self.write.check_fork(&write)?;
     self.net.check_fork(&net)?;
@@ -715,6 +715,10 @@ fn check_host_and_port_list(
       && allowlist.contains(&format!("{}:{}", host, port.unwrap())))
 }
 
+fn permission_escalation_error() -> ErrBox {
+  ErrBox::new("PermissionDenied", "Arguments escalate parent permissions")
+}
+
 #[cfg(test)]
 mod tests {
   use super::*;
diff --git a/cli/repl.rs b/cli/repl.rs
index 614921d4d..28b99cf07 100644
--- a/cli/repl.rs
+++ b/cli/repl.rs
@@ -1,6 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use crate::deno_dir::DenoDir;
-use crate::op_error::OpError;
 use deno_core::ErrBox;
 use rustyline::Editor;
 use std::fs;
@@ -42,11 +41,11 @@ impl Repl {
       .map(|_| debug!("Saved REPL history to: {:?}", self.history_file))
       .map_err(|e| {
         eprintln!("Unable to save REPL history: {:?} {}", self.history_file, e);
-        ErrBox::from(e)
+        e.into()
       })
   }
 
-  pub fn readline(&mut self, prompt: &str) -> Result<String, OpError> {
+  pub fn readline(&mut self, prompt: &str) -> Result<String, ErrBox> {
     self
       .editor
       .readline(&prompt)
@@ -54,7 +53,8 @@ impl Repl {
         self.editor.add_history_entry(line.clone());
         line
       })
-      .map_err(OpError::from)
+      .map_err(ErrBox::from)
+
     // Forward error to TS side for processing
   }
 }
diff --git a/cli/resolve_addr.rs b/cli/resolve_addr.rs
index 3081ef431..a25bf7454 100644
--- a/cli/resolve_addr.rs
+++ b/cli/resolve_addr.rs
@@ -1,10 +1,10 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-use crate::op_error::OpError;
+use deno_core::ErrBox;
 use std::net::SocketAddr;
 use std::net::ToSocketAddrs;
 
 /// Resolve network address. Returns a future.
-pub fn resolve_addr(hostname: &str, port: u16) -> Result<SocketAddr, OpError> {
+pub fn resolve_addr(hostname: &str, port: u16) -> Result<SocketAddr, ErrBox> {
   // Default to localhost if given just the port. Example: ":80"
   let addr: &str = if !hostname.is_empty() {
     &hostname
@@ -21,7 +21,7 @@ pub fn resolve_addr(hostname: &str, port: u16) -> Result<SocketAddr, OpError> {
     addr
   };
   let addr_port_pair = (addr, port);
-  let mut iter = addr_port_pair.to_socket_addrs().map_err(OpError::from)?;
+  let mut iter = addr_port_pair.to_socket_addrs()?;
   Ok(iter.next().unwrap())
 }
 
diff --git a/cli/rt/01_errors.js b/cli/rt/01_errors.js
index fb2bb78c2..d5933069b 100644
--- a/cli/rt/01_errors.js
+++ b/cli/rt/01_errors.js
@@ -127,6 +127,13 @@
     }
   }
 
+  class NotSupported extends Error {
+    constructor(msg) {
+      super(msg);
+      this.name = "NotSupported";
+    }
+  }
+
   const errors = {
     NotFound,
     PermissionDenied,
@@ -146,6 +153,7 @@
     BadResource,
     Http,
     Busy,
+    NotSupported,
   };
 
   window.__bootstrap.errors = {
diff --git a/cli/rt/10_dispatch_minimal.js b/cli/rt/10_dispatch_minimal.js
index 0a0a4f99f..072285256 100644
--- a/cli/rt/10_dispatch_minimal.js
+++ b/cli/rt/10_dispatch_minimal.js
@@ -31,11 +31,11 @@
     let err;
 
     if (arg < 0) {
-      const codeLen = result;
-      const codeAndMessage = decoder.decode(ui8.subarray(12));
-      const errorCode = codeAndMessage.slice(0, codeLen);
-      const message = codeAndMessage.slice(codeLen);
-      err = { kind: errorCode, message };
+      const classLen = result;
+      const classAndMessage = decoder.decode(ui8.subarray(12));
+      const errorClass = classAndMessage.slice(0, classLen);
+      const message = classAndMessage.slice(classLen);
+      err = { kind: errorClass, message };
     } else if (ui8.length != 12) {
       throw new TypeError("Malformed response message");
     }
@@ -72,11 +72,7 @@
     promise.resolve(record);
   }
 
-  async function sendAsync(
-    opName,
-    arg,
-    zeroCopy,
-  ) {
+  async function sendAsync(opName, arg, zeroCopy) {
     const promiseId = nextPromiseId(); // AKA cmdId
     scratch32[0] = promiseId;
     scratch32[1] = arg;
@@ -96,11 +92,7 @@
     return unwrapResponse(res);
   }
 
-  function sendSync(
-    opName,
-    arg,
-    zeroCopy,
-  ) {
+  function sendSync(opName, arg, zeroCopy) {
     scratch32[0] = 0; // promiseId 0 indicates sync
     scratch32[1] = arg;
     const res = core.dispatchByName(opName, scratchBytes, zeroCopy);
diff --git a/cli/rt/99_main.js b/cli/rt/99_main.js
index 18cc1d251..846216ec4 100644
--- a/cli/rt/99_main.js
+++ b/cli/rt/99_main.js
@@ -195,10 +195,14 @@ delete Object.prototype.__proto__;
     core.registerErrorClass("UnexpectedEof", errors.UnexpectedEof);
     core.registerErrorClass("BadResource", errors.BadResource);
     core.registerErrorClass("Http", errors.Http);
-    core.registerErrorClass("URIError", URIError);
-    core.registerErrorClass("TypeError", TypeError);
-    core.registerErrorClass("Other", Error);
     core.registerErrorClass("Busy", errors.Busy);
+    core.registerErrorClass("NotSupported", errors.NotSupported);
+    core.registerErrorClass("Error", Error);
+    core.registerErrorClass("RangeError", RangeError);
+    core.registerErrorClass("ReferenceError", ReferenceError);
+    core.registerErrorClass("SyntaxError", SyntaxError);
+    core.registerErrorClass("TypeError", TypeError);
+    core.registerErrorClass("URIError", URIError);
   }
 
   // https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope
diff --git a/cli/signal.rs b/cli/signal.rs
index f74f9ab26..fcc70d00e 100644
--- a/cli/signal.rs
+++ b/cli/signal.rs
@@ -1,5 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-use crate::op_error::OpError;
+use deno_core::ErrBox;
 
 #[cfg(not(unix))]
 const SIGINT: i32 = 2;
@@ -19,37 +19,37 @@ use winapi::{
 };
 
 #[cfg(unix)]
-pub fn kill(pid: i32, signo: i32) -> Result<(), OpError> {
+pub fn kill(pid: i32, signo: i32) -> Result<(), ErrBox> {
   use nix::sys::signal::{kill as unix_kill, Signal};
   use nix::unistd::Pid;
   use std::convert::TryFrom;
   let sig = Signal::try_from(signo)?;
-  unix_kill(Pid::from_raw(pid), Option::Some(sig)).map_err(OpError::from)
+  unix_kill(Pid::from_raw(pid), Option::Some(sig)).map_err(ErrBox::from)
 }
 
 #[cfg(not(unix))]
-pub fn kill(pid: i32, signal: i32) -> Result<(), OpError> {
+pub fn kill(pid: i32, signal: i32) -> Result<(), ErrBox> {
   match signal {
     SIGINT | SIGKILL | SIGTERM => {
       if pid <= 0 {
-        return Err(OpError::type_error("unsupported pid".to_string()));
+        return Err(ErrBox::type_error("unsupported pid"));
       }
       unsafe {
         let handle = OpenProcess(PROCESS_TERMINATE, 0, pid as DWORD);
         if handle.is_null() {
-          return Err(OpError::from(std::io::Error::last_os_error()));
+          return Err(ErrBox::last_os_error());
         }
         if TerminateProcess(handle, 1) == 0 {
           CloseHandle(handle);
-          return Err(OpError::from(std::io::Error::last_os_error()));
+          return Err(ErrBox::last_os_error());
         }
         if CloseHandle(handle) == 0 {
-          return Err(OpError::from(std::io::Error::last_os_error()));
+          return Err(ErrBox::last_os_error());
         }
       }
     }
     _ => {
-      return Err(OpError::type_error("unsupported signal".to_string()));
+      return Err(ErrBox::type_error("unsupported signal".to_string()));
     }
   }
   Ok(())
diff --git a/cli/state.rs b/cli/state.rs
index 055c09916..cb8d507f1 100644
--- a/cli/state.rs
+++ b/cli/state.rs
@@ -5,7 +5,6 @@ use crate::global_timer::GlobalTimer;
 use crate::http_util::create_http_client;
 use crate::import_map::ImportMap;
 use crate::metrics::Metrics;
-use crate::op_error::OpError;
 use crate::ops::serialize_result;
 use crate::ops::JsonOp;
 use crate::ops::MinimalOp;
@@ -64,7 +63,7 @@ impl State {
     dispatcher: D,
   ) -> impl Fn(&mut deno_core::CoreIsolateState, &mut [ZeroCopyBuf]) -> Op
   where
-    D: Fn(&Rc<State>, Value, &mut [ZeroCopyBuf]) -> Result<JsonOp, OpError>,
+    D: Fn(&Rc<State>, Value, &mut [ZeroCopyBuf]) -> Result<JsonOp, ErrBox>,
   {
     use crate::ops::json_op;
     self.core_op(json_op(self.stateful_op(dispatcher)))
@@ -81,18 +80,22 @@ impl State {
       &mut ResourceTable,
       Value,
       &mut [ZeroCopyBuf],
-    ) -> Result<Value, OpError>,
+    ) -> Result<Value, ErrBox>,
   {
     let state = self.clone();
     let resource_table = resource_table.clone();
 
-    move |_: &mut CoreIsolateState, bufs: &mut [ZeroCopyBuf]| {
+    move |isolate_state: &mut CoreIsolateState, bufs: &mut [ZeroCopyBuf]| {
+      let rust_err_to_json_fn = isolate_state.rust_err_to_json_fn;
       // The first buffer should contain JSON encoded op arguments; parse them.
       let args: Value = match serde_json::from_slice(&bufs[0]) {
         Ok(v) => v,
         Err(e) => {
-          let e = OpError::from(e);
-          return Op::Sync(serialize_result(None, Err(e)));
+          return Op::Sync(serialize_result(
+            rust_err_to_json_fn,
+            None,
+            Err(e.into()),
+          ));
         }
       };
 
@@ -103,7 +106,7 @@ impl State {
         dispatcher(&state, &mut *resource_table.borrow_mut(), args, zero_copy);
 
       // Convert to Op.
-      Op::Sync(serialize_result(None, result))
+      Op::Sync(serialize_result(rust_err_to_json_fn, None, result))
     }
   }
 
@@ -115,18 +118,19 @@ impl State {
   where
     D:
       FnOnce(Rc<State>, Rc<RefCell<ResourceTable>>, Value, BufVec) -> F + Clone,
-    F: Future<Output = Result<Value, OpError>> + 'static,
+    F: Future<Output = Result<Value, ErrBox>> + 'static,
   {
     let state = self.clone();
     let resource_table = resource_table.clone();
 
-    move |_: &mut CoreIsolateState, bufs: &mut [ZeroCopyBuf]| {
+    move |isolate_state: &mut CoreIsolateState, bufs: &mut [ZeroCopyBuf]| {
+      let rust_err_to_json_fn = isolate_state.rust_err_to_json_fn;
       // The first buffer should contain JSON encoded op arguments; parse them.
       let args: Value = match serde_json::from_slice(&bufs[0]) {
         Ok(v) => v,
         Err(e) => {
-          let e = OpError::from(e);
-          return Op::Sync(serialize_result(None, Err(e)));
+          let e = e.into();
+          return Op::Sync(serialize_result(rust_err_to_json_fn, None, Err(e)));
         }
       };
 
@@ -134,8 +138,8 @@ impl State {
       let promise_id = match args.get("promiseId").and_then(|v| v.as_u64()) {
         Some(i) => i,
         None => {
-          let e = OpError::type_error("`promiseId` invalid/missing".to_owned());
-          return Op::Sync(serialize_result(None, Err(e)));
+          let e = ErrBox::new("TypeError", "`promiseId` invalid/missing");
+          return Op::Sync(serialize_result(rust_err_to_json_fn, None, Err(e)));
         }
       };
 
@@ -152,8 +156,10 @@ impl State {
 
       // Convert to Op.
       Op::Async(
-        async move { serialize_result(Some(promise_id), fut.await) }
-          .boxed_local(),
+        async move {
+          serialize_result(rust_err_to_json_fn, Some(promise_id), fut.await)
+        }
+        .boxed_local(),
       )
     }
   }
@@ -168,7 +174,7 @@ impl State {
       &Rc<State>,
       Value,
       &mut [ZeroCopyBuf],
-    ) -> Result<JsonOp, OpError>,
+    ) -> Result<JsonOp, ErrBox>,
   {
     use crate::ops::json_op;
     self.core_op(json_op(self.stateful_op2(dispatcher)))
@@ -276,15 +282,15 @@ impl State {
     &mut deno_core::CoreIsolateState,
     Value,
     &mut [ZeroCopyBuf],
-  ) -> Result<JsonOp, OpError>
+  ) -> Result<JsonOp, ErrBox>
   where
-    D: Fn(&Rc<State>, Value, &mut [ZeroCopyBuf]) -> Result<JsonOp, OpError>,
+    D: Fn(&Rc<State>, Value, &mut [ZeroCopyBuf]) -> Result<JsonOp, ErrBox>,
   {
     let state = self.clone();
     move |_isolate_state: &mut deno_core::CoreIsolateState,
           args: Value,
           zero_copy: &mut [ZeroCopyBuf]|
-          -> Result<JsonOp, OpError> { dispatcher(&state, args, zero_copy) }
+          -> Result<JsonOp, ErrBox> { dispatcher(&state, args, zero_copy) }
   }
 
   pub fn stateful_op2<D>(
@@ -294,20 +300,20 @@ impl State {
     &mut deno_core::CoreIsolateState,
     Value,
     &mut [ZeroCopyBuf],
-  ) -> Result<JsonOp, OpError>
+  ) -> Result<JsonOp, ErrBox>
   where
     D: Fn(
       &mut deno_core::CoreIsolateState,
       &Rc<State>,
       Value,
       &mut [ZeroCopyBuf],
-    ) -> Result<JsonOp, OpError>,
+    ) -> Result<JsonOp, ErrBox>,
   {
     let state = self.clone();
     move |isolate_state: &mut deno_core::CoreIsolateState,
           args: Value,
           zero_copy: &mut [ZeroCopyBuf]|
-          -> Result<JsonOp, OpError> {
+          -> Result<JsonOp, ErrBox> {
       dispatcher(isolate_state, &state, args, zero_copy)
     }
   }
@@ -488,7 +494,7 @@ impl State {
   }
 
   #[inline]
-  pub fn check_read(&self, path: &Path) -> Result<(), OpError> {
+  pub fn check_read(&self, path: &Path) -> Result<(), ErrBox> {
     self.permissions.borrow().check_read(path)
   }
 
@@ -499,49 +505,49 @@ impl State {
     &self,
     path: &Path,
     display: &str,
-  ) -> Result<(), OpError> {
+  ) -> Result<(), ErrBox> {
     self.permissions.borrow().check_read_blind(path, display)
   }
 
   #[inline]
-  pub fn check_write(&self, path: &Path) -> Result<(), OpError> {
+  pub fn check_write(&self, path: &Path) -> Result<(), ErrBox> {
     self.permissions.borrow().check_write(path)
   }
 
   #[inline]
-  pub fn check_env(&self) -> Result<(), OpError> {
+  pub fn check_env(&self) -> Result<(), ErrBox> {
     self.permissions.borrow().check_env()
   }
 
   #[inline]
-  pub fn check_net(&self, hostname: &str, port: u16) -> Result<(), OpError> {
+  pub fn check_net(&self, hostname: &str, port: u16) -> Result<(), ErrBox> {
     self.permissions.borrow().check_net(hostname, port)
   }
 
   #[inline]
-  pub fn check_net_url(&self, url: &url::Url) -> Result<(), OpError> {
+  pub fn check_net_url(&self, url: &url::Url) -> Result<(), ErrBox> {
     self.permissions.borrow().check_net_url(url)
   }
 
   #[inline]
-  pub fn check_run(&self) -> Result<(), OpError> {
+  pub fn check_run(&self) -> Result<(), ErrBox> {
     self.permissions.borrow().check_run()
   }
 
   #[inline]
-  pub fn check_hrtime(&self) -> Result<(), OpError> {
+  pub fn check_hrtime(&self) -> Result<(), ErrBox> {
     self.permissions.borrow().check_hrtime()
   }
 
   #[inline]
-  pub fn check_plugin(&self, filename: &Path) -> Result<(), OpError> {
+  pub fn check_plugin(&self, filename: &Path) -> Result<(), ErrBox> {
     self.permissions.borrow().check_plugin(filename)
   }
 
   pub fn check_dyn_import(
     &self,
     module_specifier: &ModuleSpecifier,
-  ) -> Result<(), OpError> {
+  ) -> Result<(), ErrBox> {
     let u = module_specifier.as_url();
     // TODO(bartlomieju): temporary fix to prevent hitting `unreachable`
     // statement that is actually reachable...
diff --git a/cli/swc_util.rs b/cli/swc_util.rs
index 934bed01a..7c7d01832 100644
--- a/cli/swc_util.rs
+++ b/cli/swc_util.rs
@@ -236,8 +236,7 @@ impl AstParser {
     media_type: MediaType,
     source_code: &str,
   ) -> Result<String, ErrBox> {
-    let parse_result = self.parse_module(file_name, media_type, source_code);
-    let module = parse_result?;
+    let module = self.parse_module(file_name, media_type, source_code)?;
     let program = Program::Module(module);
     let mut compiler_pass =
       chain!(typescript::strip(), fixer(Some(&self.comments)));
@@ -261,7 +260,7 @@ impl AstParser {
       };
       program.emit_with(&mut emitter)?;
     }
-    let mut src = String::from_utf8(buf).map_err(ErrBox::from)?;
+    let mut src = String::from_utf8(buf)?;
     {
       let mut buf = vec![];
       self
diff --git a/cli/tests/unit/dispatch_json_test.ts b/cli/tests/unit/dispatch_json_test.ts
index e5200aa5b..fe05122d5 100644
--- a/cli/tests/unit/dispatch_json_test.ts
+++ b/cli/tests/unit/dispatch_json_test.ts
@@ -39,7 +39,7 @@ unitTest(function malformedJsonControlBuffer(): void {
   const resText = new TextDecoder().decode(resBuf);
   const resObj = JSON.parse(resText);
   assertStrictEquals(resObj.ok, undefined);
-  assertStrictEquals(resObj.err.kind, "TypeError");
+  assertStrictEquals(resObj.err.kind, "SyntaxError");
   assertMatch(resObj.err.message, /\bexpected value\b/);
 });
 
diff --git a/cli/tsc.rs b/cli/tsc.rs
index 5fa8b67a3..d509d99ce 100644
--- a/cli/tsc.rs
+++ b/cli/tsc.rs
@@ -12,7 +12,6 @@ use crate::module_graph::ModuleGraph;
 use crate::module_graph::ModuleGraphLoader;
 use crate::msg;
 use crate::msg::MediaType;
-use crate::op_error::OpError;
 use crate::ops;
 use crate::permissions::Permissions;
 use crate::source_maps::SourceMapGetter;
@@ -618,7 +617,7 @@ impl TsCompiler {
     let compile_response: CompileResponse = serde_json::from_str(&json_str)?;
 
     if !compile_response.diagnostics.items.is_empty() {
-      return Err(ErrBox::from(compile_response.diagnostics));
+      return Err(ErrBox::error(compile_response.diagnostics.to_string()));
     }
 
     maybe_log_stats(compile_response.stats);
@@ -722,7 +721,7 @@ impl TsCompiler {
     maybe_log_stats(bundle_response.stats);
 
     if !bundle_response.diagnostics.items.is_empty() {
-      return Err(ErrBox::from(bundle_response.diagnostics));
+      return Err(ErrBox::error(bundle_response.diagnostics.to_string()));
     }
 
     assert!(bundle_response.bundle_output.is_some());
@@ -1071,7 +1070,7 @@ async fn create_runtime_module_graph(
   root_name: &str,
   sources: &Option<HashMap<String, String>>,
   maybe_options: &Option<String>,
-) -> Result<(Vec<String>, ModuleGraph), OpError> {
+) -> Result<(Vec<String>, ModuleGraph), ErrBox> {
   let mut root_names = vec![];
   let mut module_graph_loader = ModuleGraphLoader::new(
     global_state.file_fetcher.clone(),
@@ -1117,14 +1116,14 @@ async fn create_runtime_module_graph(
 }
 
 /// Because TS compiler can raise runtime error, we need to
-/// manually convert formatted JSError into and OpError.
-fn js_error_to_op_error(error: ErrBox) -> OpError {
+/// manually convert formatted JSError into and ErrBox.
+fn js_error_to_errbox(error: ErrBox) -> ErrBox {
   match error.downcast::<JSError>() {
     Ok(js_error) => {
       let msg = format!("Error in TS compiler:\n{}", js_error);
-      OpError::other(msg)
+      ErrBox::error(msg)
     }
-    Err(error) => error.into(),
+    Err(error) => error,
   }
 }
 
@@ -1135,7 +1134,7 @@ pub async fn runtime_compile(
   root_name: &str,
   sources: &Option<HashMap<String, String>>,
   maybe_options: &Option<String>,
-) -> Result<Value, OpError> {
+) -> Result<Value, ErrBox> {
   let (root_names, module_graph) = create_runtime_module_graph(
     &global_state,
     permissions.clone(),
@@ -1161,7 +1160,7 @@ pub async fn runtime_compile(
 
   let json_str = execute_in_same_thread(global_state, permissions, req_msg)
     .await
-    .map_err(js_error_to_op_error)?;
+    .map_err(js_error_to_errbox)?;
 
   let response: RuntimeCompileResponse = serde_json::from_str(&json_str)?;
 
@@ -1182,7 +1181,7 @@ pub async fn runtime_bundle(
   root_name: &str,
   sources: &Option<HashMap<String, String>>,
   maybe_options: &Option<String>,
-) -> Result<Value, OpError> {
+) -> Result<Value, ErrBox> {
   let (root_names, module_graph) = create_runtime_module_graph(
     &global_state,
     permissions.clone(),
@@ -1206,7 +1205,7 @@ pub async fn runtime_bundle(
 
   let json_str = execute_in_same_thread(global_state, permissions, req_msg)
     .await
-    .map_err(js_error_to_op_error)?;
+    .map_err(js_error_to_errbox)?;
   let _response: RuntimeBundleResponse = serde_json::from_str(&json_str)?;
   // We're returning `Ok()` instead of `Err()` because it's not runtime
   // error if there were diagnostics produced; we want to let user handle
@@ -1220,7 +1219,7 @@ pub async fn runtime_transpile(
   permissions: Permissions,
   sources: &HashMap<String, String>,
   options: &Option<String>,
-) -> Result<Value, OpError> {
+) -> Result<Value, ErrBox> {
   let req_msg = json!({
     "type": msg::CompilerRequestType::RuntimeTranspile,
     "sources": sources,
@@ -1230,7 +1229,7 @@ pub async fn runtime_transpile(
 
   let json_str = execute_in_same_thread(global_state, permissions, req_msg)
     .await
-    .map_err(js_error_to_op_error)?;
+    .map_err(js_error_to_errbox)?;
   let v = serde_json::from_str::<serde_json::Value>(&json_str)
     .expect("Error decoding JSON string.");
   Ok(v)
diff --git a/cli/upgrade.rs b/cli/upgrade.rs
index 244bf6c8a..1009e5c77 100644
--- a/cli/upgrade.rs
+++ b/cli/upgrade.rs
@@ -10,7 +10,6 @@ extern crate semver_parser;
 use crate::futures::FutureExt;
 use crate::http_util::fetch_once;
 use crate::http_util::FetchOnceResult;
-use crate::op_error::OpError;
 use crate::ErrBox;
 use regex::Regex;
 use reqwest::{redirect::Policy, Client};
@@ -166,7 +165,7 @@ fn compose_url_to_exec(version: &Version) -> Result<Url, ErrBox> {
     "https://github.com/denoland/deno/releases/download/v{}/{}",
     version, ARCHIVE_NAME
   );
-  Ok(Url::parse(&s)?)
+  Url::parse(&s).map_err(ErrBox::from)
 }
 
 fn find_version(text: &str) -> Result<String, ErrBox> {
@@ -175,10 +174,10 @@ fn find_version(text: &str) -> Result<String, ErrBox> {
     let mat = _mat.as_str();
     return Ok(mat[1..mat.len() - 1].to_string());
   }
-  Err(OpError::other("Cannot read latest tag version".to_string()).into())
+  Err(ErrBox::new("NotFound", "Cannot read latest tag version"))
 }
 
-fn unpack(archive_data: Vec<u8>) -> Result<PathBuf, ErrBox> {
+fn unpack(archive_data: Vec<u8>) -> Result<PathBuf, std::io::Error> {
   // We use into_path so that the tempdir is not automatically deleted. This is
   // useful for debugging upgrade, but also so this function can return a path
   // to the newly uncompressed file without fear of the tempdir being deleted.
@@ -244,7 +243,7 @@ fn unpack(archive_data: Vec<u8>) -> Result<PathBuf, ErrBox> {
   Ok(exe_path)
 }
 
-fn replace_exe(new: &Path, old: &Path) -> Result<(), ErrBox> {
+fn replace_exe(new: &Path, old: &Path) -> Result<(), std::io::Error> {
   if cfg!(windows) {
     // On windows you cannot replace the currently running executable.
     // so first we rename it to deno.old.exe
diff --git a/cli/worker.rs b/cli/worker.rs
index 928d3316f..cfdcaeda7 100644
--- a/cli/worker.rs
+++ b/cli/worker.rs
@@ -1,4 +1,5 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use crate::errors::rust_err_to_json;
 use crate::fmt_errors::JSError;
 use crate::global_state::GlobalState;
 use crate::inspector::DenoInspector;
@@ -51,7 +52,8 @@ impl WorkerHandle {
   /// Post message to worker as a host.
   pub fn post_message(&self, buf: Buf) -> Result<(), ErrBox> {
     let mut sender = self.sender.clone();
-    sender.try_send(buf).map_err(ErrBox::from)
+    sender.try_send(buf)?;
+    Ok(())
   }
 
   /// Get the event with lock.
@@ -114,6 +116,7 @@ impl Worker {
       core_state.set_js_error_create_fn(move |core_js_error| {
         JSError::create(core_js_error, &global_state.ts_compiler)
       });
+      core_state.set_rust_err_to_json_fn(&rust_err_to_json);
     }
 
     let inspector = {