diff --git a/core/01_core.js b/core/01_core.js
index 0e823f54a8..1dfb88c99c 100644
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -127,6 +127,18 @@
     errorMap[className] = errorBuilder;
   }
 
+  function buildCustomError(className, message, code) {
+    const error = errorMap[className]?.(message);
+    // Strip buildCustomError() calls from stack trace
+    if (typeof error == "object") {
+      ErrorCaptureStackTrace(error, buildCustomError);
+      if (code) {
+        error.code = code;
+      }
+    }
+    return error;
+  }
+
   function unwrapOpResult(res) {
     // .$err_class_name is a special key that should only exist on errors
     if (res?.$err_class_name) {
@@ -168,7 +180,7 @@
   }
 
   function opSync(opName, ...args) {
-    return unwrapOpResult(ops[opName](...args));
+    return ops[opName](...args);
   }
 
   function refOp(promiseId) {
@@ -229,6 +241,7 @@
     metrics,
     registerErrorBuilder,
     registerErrorClass,
+    buildCustomError,
     opresolve,
     BadResource,
     BadResourcePrototype,
diff --git a/core/error.rs b/core/error.rs
index 664cb5c0be..bc8a3195ba 100644
--- a/core/error.rs
+++ b/core/error.rs
@@ -1,5 +1,7 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
 
+use crate::runtime::GetErrorClassFn;
+use crate::runtime::JsRealm;
 use crate::runtime::JsRuntime;
 use crate::source_map::apply_source_map;
 use crate::source_map::get_source_line;
@@ -91,6 +93,30 @@ pub fn get_custom_error_class(error: &Error) -> Option<&'static str> {
   error.downcast_ref::<CustomError>().map(|e| e.class)
 }
 
+pub fn to_v8_error<'a>(
+  scope: &mut v8::HandleScope<'a>,
+  get_class: GetErrorClassFn,
+  error: &Error,
+) -> v8::Local<'a, v8::Value> {
+  let cb = JsRealm::state_from_scope(scope)
+    .borrow()
+    .js_build_custom_error_cb
+    .clone()
+    .expect("Custom error builder must be set");
+  let cb = cb.open(scope);
+  let this = v8::undefined(scope).into();
+  let class = v8::String::new(scope, get_class(error)).unwrap();
+  let message = v8::String::new(scope, &error.to_string()).unwrap();
+  let mut args = vec![class.into(), message.into()];
+  if let Some(code) = crate::error_codes::get_error_code(error) {
+    args.push(v8::String::new(scope, code).unwrap().into());
+  }
+  let exception = cb
+    .call(scope, this, &args)
+    .expect("Custom error class must have a builder registered");
+  exception
+}
+
 /// A `JsError` represents an exception coming from V8, with stack frames and
 /// line numbers. The deno_cli crate defines another `JsError` type, which wraps
 /// the one defined here, that adds source map support and colorful formatting.
diff --git a/core/ops_builtin_v8.rs b/core/ops_builtin_v8.rs
index f2d28346e4..b828f908d6 100644
--- a/core/ops_builtin_v8.rs
+++ b/core/ops_builtin_v8.rs
@@ -473,7 +473,8 @@ fn op_serialize(
     value_serializer.write_value(scope.get_current_context(), value.v8_value);
   if scope.has_caught() || scope.has_terminated() {
     scope.rethrow();
-    Err(type_error("unreachable"))
+    // Dummy value, this result will be discarded because an error was thrown.
+    Ok(ZeroCopyBuf::empty())
   } else if let Some(true) = ret {
     let vector = value_serializer.release();
     Ok(vector.into())
diff --git a/core/runtime.rs b/core/runtime.rs
index b13ed0b7ea..3f3caac5e5 100644
--- a/core/runtime.rs
+++ b/core/runtime.rs
@@ -150,6 +150,7 @@ pub type CompiledWasmModuleStore = CrossIsolateStore<v8::CompiledWasmModule>;
 #[derive(Default)]
 pub(crate) struct ContextState {
   js_recv_cb: Option<v8::Global<v8::Function>>,
+  pub(crate) js_build_custom_error_cb: Option<v8::Global<v8::Function>>,
   // TODO(andreubotella): Move the rest of Option<Global<Function>> fields from
   // JsRuntimeState to this struct.
   pub(crate) unrefed_ops: HashSet<i32>,
@@ -653,16 +654,25 @@ impl JsRuntime {
 
   /// Grabs a reference to core.js' opresolve & syncOpsCache()
   fn init_cbs(&mut self, realm: &JsRealm) {
-    let recv_cb = {
+    let (recv_cb, build_custom_error_cb) = {
       let scope = &mut realm.handle_scope(self.v8_isolate());
       let recv_cb =
         Self::grab_global::<v8::Function>(scope, "Deno.core.opresolve")
           .expect("Deno.core.opresolve is undefined in the realm");
-      v8::Global::new(scope, recv_cb)
+      let recv_cb = v8::Global::new(scope, recv_cb);
+      let build_custom_error_cb =
+        Self::grab_global::<v8::Function>(scope, "Deno.core.buildCustomError")
+          .expect("Deno.core.buildCustomError is undefined in the realm");
+      let build_custom_error_cb = v8::Global::new(scope, build_custom_error_cb);
+      (recv_cb, build_custom_error_cb)
     };
     // Put global handle in callback state
     let state = realm.state(self.v8_isolate());
     state.borrow_mut().js_recv_cb.replace(recv_cb);
+    state
+      .borrow_mut()
+      .js_build_custom_error_cb
+      .replace(build_custom_error_cb);
   }
 
   /// Returns the runtime's op state, which can be used to maintain ops
@@ -737,6 +747,9 @@ impl JsRuntime {
           let realm = JsRealm::new(context.clone());
           let realm_state = realm.state(self.v8_isolate());
           std::mem::take(&mut realm_state.borrow_mut().js_recv_cb);
+          std::mem::take(
+            &mut realm_state.borrow_mut().js_build_custom_error_cb,
+          );
           context
             .open(self.v8_isolate())
             .clear_all_slots(self.v8_isolate());
@@ -3424,7 +3437,7 @@ assertEquals(1, notify_return_value);
         Deno.core.opSync("op_set_promise_reject_callback", (type, promise, reason) => {
           Deno.core.opSync("op_promise_reject");
         });
-        
+
         throw new Error('top level throw');
         "#;
 
diff --git a/ops/lib.rs b/ops/lib.rs
index fdafca1659..42913160b4 100644
--- a/ops/lib.rs
+++ b/ops/lib.rs
@@ -399,8 +399,8 @@ fn codegen_sync_ret(
         #ok_block
       },
       Err(err) => {
-        let err = #core::OpError::new(op_state.get_error_class_fn, err);
-        rv.set(#core::serde_v8::to_v8(scope, err).unwrap());
+        let exception = #core::error::to_v8_error(scope, op_state.get_error_class_fn, &err);
+        scope.throw_exception(exception);
       },
     };
   }