diff --git a/CHANGELOG.md b/CHANGELOG.md
index e705499813e..a4e954630e4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,13 @@
   stack trace rather than propagate a `null` value.
   Error handling functions need no longer be prepared for `null` stack traces.
 
+* **Breaking change**: [#40681](https://github.com/dart-lang/sdk/issues/40681)
+  The `runZoned` function is split into two functions: `runZoned` and
+  `runZonedGuarded`, where the latter has a required `onError` parameter,
+  and the former has none.
+  This prepares the functions for Null Safety where the two functions will
+  differ in the nullability of their return types.
+
 #### `dart:core`
 
 * Adds `StackTrace.empty` constant which is the stack trace used as default
@@ -137,6 +144,18 @@ used (see Issue [39627][]).
     address in byte format for Internet addresses or raw file path for Unix
     domain addresses.
 
+* **Breaking change** [#40681](https://github.com/dart-lang/sdk/issues/40681)
+  The static method `runZoned` and `runWithHttpOverrides` on `HttpOverrides`
+  no longer accept `zoneSpecification` and `onError` parameters.
+  Use the `runZoned` or `runZonedGuarded` functions from `dart:async`
+  directly if needing to specify those.
+
+* **Breaking change** [#40681](https://github.com/dart-lang/sdk/issues/40681)
+  The static method `runZoned` and `runWithIOOverrides` on `IOOverrides`
+  no longer accept `zoneSpecification` and `onError` parameters.
+  Use the `runZoned` or `runZonedGuarded` functions from `dart:async`
+  directly if needing to specify those.
+
 #### `dart:mirrors`
 
 * Added `MirrorSystem.neverType`.
@@ -188,7 +207,7 @@ additional details see the [announcement].
   Use of this library on the web has been unsupported and prevented by the Dart
   build systems since Dart v2.0.0. All known exception cases have been cleaned
   up. This change makes DDC and dart2js now behave consistently.
-  
+
   The library can still be imported on web apps, but all APIs throw. In a future
   breaking change release, imports to this library will likely become a
   compile-time error.
diff --git a/pkg/analysis_server/lib/src/analysis_server.dart b/pkg/analysis_server/lib/src/analysis_server.dart
index b577f21a86d..a2dd3bffa2d 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -312,7 +312,7 @@ class AnalysisServer extends AbstractAnalysisServer {
   /// Handle a [request] that was read from the communication channel.
   void handleRequest(Request request) {
     performance.logRequestTiming(request.clientRequestTime);
-    runZoned(() {
+    runZonedGuarded(() {
       ServerPerformanceStatistics.serverRequests.makeCurrentWhile(() {
         int count = handlers.length;
         for (int i = 0; i < count; i++) {
@@ -341,7 +341,7 @@ class AnalysisServer extends AbstractAnalysisServer {
         }
         channel.sendResponse(Response.unknownRequest(request));
       });
-    }, onError: (exception, stackTrace) {
+    }, (exception, stackTrace) {
       AnalysisEngine.instance.instrumentationService.logException(
           FatalException('Failed to handle request: ${request.method}',
               exception, stackTrace));
diff --git a/pkg/analysis_server/lib/src/channel/byte_stream_channel.dart b/pkg/analysis_server/lib/src/channel/byte_stream_channel.dart
index 343f98aa0a9..57bf82000d6 100644
--- a/pkg/analysis_server/lib/src/channel/byte_stream_channel.dart
+++ b/pkg/analysis_server/lib/src/channel/byte_stream_channel.dart
@@ -144,9 +144,9 @@ class ByteStreamServerChannel implements ServerCommunicationChannel {
 
   /// Send the string [s] to [_output] followed by a newline.
   void _outputLine(String s) {
-    runZoned(() {
+    runZonedGuarded(() {
       _output.writeln(s);
-    }, onError: (e) {
+    }, (e, s) {
       close();
     });
   }
diff --git a/pkg/analysis_server/lib/src/domain_completion.dart b/pkg/analysis_server/lib/src/domain_completion.dart
index dd193c40771..d4f6632f774 100644
--- a/pkg/analysis_server/lib/src/domain_completion.dart
+++ b/pkg/analysis_server/lib/src/domain_completion.dart
@@ -217,7 +217,7 @@ class CompletionDomainHandler extends AbstractRequestHandler {
       );
     }
 
-    return runZoned(() {
+    return runZonedGuarded(() {
       String requestName = request.method;
 
       if (requestName == COMPLETION_REQUEST_GET_SUGGESTION_DETAILS) {
@@ -233,7 +233,7 @@ class CompletionDomainHandler extends AbstractRequestHandler {
         return setSubscriptions(request);
       }
       return null;
-    }, onError: (exception, stackTrace) {
+    }, (exception, stackTrace) {
       AnalysisEngine.instance.instrumentationService.logException(
           CaughtException.withMessage(
               'Failed to handle completion domain request: ${request.method}',
diff --git a/pkg/analysis_server/lib/src/edit/edit_domain.dart b/pkg/analysis_server/lib/src/edit/edit_domain.dart
index 9a8a5ae0cbb..fb240a19127 100644
--- a/pkg/analysis_server/lib/src/edit/edit_domain.dart
+++ b/pkg/analysis_server/lib/src/edit/edit_domain.dart
@@ -942,7 +942,7 @@ class _RefactoringManager {
           ?.sendEvent('refactor', params.kind.name.toLowerCase());
     }
 
-    runZoned(() async {
+    runZonedGuarded(() async {
       // TODO(brianwilkerson) Determine whether this await is necessary.
       await null;
       await _init(params.kind, file, params.offset, params.length);
@@ -990,7 +990,7 @@ class _RefactoringManager {
       _checkForReset_afterCreateChange();
       result.potentialEdits = nullIfEmpty(refactoring.potentialEditIds);
       _sendResultResponse();
-    }, onError: (exception, stackTrace) {
+    }, (exception, stackTrace) {
       if (exception is _ResetError ||
           exception is InconsistentAnalysisException) {
         cancel();
diff --git a/pkg/analysis_server/lib/src/lsp/channel/lsp_byte_stream_channel.dart b/pkg/analysis_server/lib/src/lsp/channel/lsp_byte_stream_channel.dart
index 9a990fd8b8f..4fb256ced7c 100644
--- a/pkg/analysis_server/lib/src/lsp/channel/lsp_byte_stream_channel.dart
+++ b/pkg/analysis_server/lib/src/lsp/channel/lsp_byte_stream_channel.dart
@@ -128,9 +128,9 @@ class LspByteStreamServerChannel implements LspServerCommunicationChannel {
 
   /// Send [bytes] to [_output].
   void _write(List<int> bytes) {
-    runZoned(
+    runZonedGuarded(
       () => _output.add(bytes),
-      onError: (e) => close(),
+      (e, s) => close(),
     );
   }
 }
diff --git a/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart b/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart
index c8a69deeb0a..b806164af93 100644
--- a/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart
+++ b/pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart
@@ -245,7 +245,7 @@ class LspAnalysisServer extends AbstractAnalysisServer {
   /// Handle a [message] that was read from the communication channel.
   void handleMessage(Message message) {
     performance.logRequestTiming(null);
-    runZoned(() {
+    runZonedGuarded(() {
       ServerPerformanceStatistics.serverRequests.makeCurrentWhile(() async {
         try {
           if (message is ResponseMessage) {
@@ -284,7 +284,7 @@ class LspAnalysisServer extends AbstractAnalysisServer {
           logException(errorMessage, error, stackTrace);
         }
       });
-    }, onError: socketError);
+    }, socketError);
   }
 
   /// Logs the error on the client using window/logMessage.
diff --git a/runtime/tests/vm/dart/causal_stacks/utils.dart b/runtime/tests/vm/dart/causal_stacks/utils.dart
index 50d9527c6b9..118ce1408a4 100644
--- a/runtime/tests/vm/dart/causal_stacks/utils.dart
+++ b/runtime/tests/vm/dart/causal_stacks/utils.dart
@@ -140,10 +140,10 @@ Future listenAsyncStarThrowAsync() async {
 
 Future<void> customErrorZone() async {
   final completer = Completer<void>();
-  runZoned(() async {
+  runZonedGuarded(() async {
     await allYield();
     completer.complete(null);
-  }, onError: (e, s) {
+  }, (e, s) {
     completer.completeError(e, s);
   });
   return completer.future;
@@ -550,7 +550,7 @@ Future<void> doTestsCausal() async {
     r'#5      _rootRun ',
     r'#6      _CustomZone.run ',
     r'#7      _runZoned ',
-    r'#8      runZoned ',
+    r'#8      runZonedGuarded ',
     r'#9      customErrorZone \(.*/utils.dart:143(:3)?\)$',
   ];
   await doTestAwait(
diff --git a/runtime/tests/vm/dart/isolate_send_function_types_test.dart b/runtime/tests/vm/dart/isolate_send_function_types_test.dart
index e8fb8fff021..e45e04550ca 100644
--- a/runtime/tests/vm/dart/isolate_send_function_types_test.dart
+++ b/runtime/tests/vm/dart/isolate_send_function_types_test.dart
@@ -14,9 +14,9 @@ main(args) async {
 
   {
     final caughtErrorCompleter = Completer<String>();
-    await runZoned(() {
+    await runZonedGuarded(() {
       Isolate.spawn(isolate, x);
-    }, onError: (e) {
+    }, (e, s) {
       caughtErrorCompleter.complete(e.toString());
     });
     Expect.equals(
diff --git a/sdk/lib/_http/overrides.dart b/sdk/lib/_http/overrides.dart
index 4112c3c56d7..8b63209c8a1 100644
--- a/sdk/lib/_http/overrides.dart
+++ b/sdk/lib/_http/overrides.dart
@@ -51,27 +51,20 @@ abstract class HttpOverrides {
   static R runZoned<R>(R body(),
       {HttpClient Function(SecurityContext) createHttpClient,
       String Function(Uri uri, Map<String, String> environment)
-          findProxyFromEnvironment,
-      ZoneSpecification zoneSpecification,
-      Function onError}) {
+          findProxyFromEnvironment}) {
     HttpOverrides overrides =
         new _HttpOverridesScope(createHttpClient, findProxyFromEnvironment);
     return _asyncRunZoned<R>(body,
-        zoneValues: {_httpOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+        zoneValues: {_httpOverridesToken: overrides});
   }
 
   /// Runs [body] in a fresh [Zone] using the overrides found in [overrides].
   ///
   /// Note that [overrides] should be an instance of a class that extends
   /// [HttpOverrides].
-  static R runWithHttpOverrides<R>(R body(), HttpOverrides overrides,
-      {ZoneSpecification zoneSpecification, Function onError}) {
+  static R runWithHttpOverrides<R>(R body(), HttpOverrides overrides) {
     return _asyncRunZoned<R>(body,
-        zoneValues: {_httpOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+        zoneValues: {_httpOverridesToken: overrides});
   }
 
   /// Returns a new [HttpClient] using the given [context].
diff --git a/sdk/lib/async/zone.dart b/sdk/lib/async/zone.dart
index 82626a6c8a2..fa7727349a9 100644
--- a/sdk/lib/async/zone.dart
+++ b/sdk/lib/async/zone.dart
@@ -1467,43 +1467,91 @@ const _rootZone = const _RootZone();
  *       var future2 = future.then((_) { throw "error in first error-zone"; });
  *       runZoned(() {
  *         var future3 = future2.catchError((e) { print("Never reached!"); });
- *       }, onError: (e) { print("unused error handler"); });
- *     }, onError: (e) { print("catches error of first error-zone."); });
+ *       }, onError: (e, s) { print("unused error handler"); });
+ *     }, onError: (e, s) { print("catches error of first error-zone."); });
  *
  * Example:
  *
  *     runZoned(() {
  *       new Future(() { throw "asynchronous error"; });
- *     }, onError: print);  // Will print "asynchronous error".
+ *     }, onError: (e, s) => print(e));  // Will print "asynchronous error".
  *
  * It is possible to manually pass an error from one error zone to another
  * by re-throwing it in the new zone. If [onError] throws, that error will
  * occur in the original zone where [runZoned] was called.
  */
 R runZoned<R>(R body(),
-    {Map zoneValues, ZoneSpecification zoneSpecification, Function onError}) {
-  if (onError == null) {
-    return _runZoned<R>(body, zoneValues, zoneSpecification);
-  }
-  void Function(Object) unaryOnError;
-  void Function(Object, StackTrace) binaryOnError;
-  if (onError is void Function(Object, StackTrace)) {
-    binaryOnError = onError;
-  } else if (onError is void Function(Object)) {
-    unaryOnError = onError;
-  } else {
-    throw new ArgumentError("onError callback must take either an Object "
-        "(the error), or both an Object (the error) and a StackTrace.");
+    {Map zoneValues,
+    ZoneSpecification zoneSpecification,
+    @Deprecated("Use runZonedGuarded instead") Function onError}) {
+  ArgumentError.checkNotNull(body, "body");
+
+  if (onError != null) {
+    void Function(Object, StackTrace) typedOnError;
+    if (onError is void Function(Object, StackTrace)) {
+      typedOnError = onError;
+    } else if (onError is void Function(Object)) {
+      typedOnError = (Object e, StackTrace _) => onError(e);
+    } else {
+      throw ArgumentError.value(onError, "onError",
+          "Should accept one error, or one error and a stack trace");
+    }
+    return runZonedGuarded(body, typedOnError,
+        zoneValues: zoneValues, zoneSpecification: zoneSpecification);
   }
+  return _runZoned<R>(body, zoneValues, zoneSpecification);
+}
+
+/**
+ * Runs [body] in its own error zone.
+ *
+ * Creates a new zone using [Zone.fork] based on [zoneSpecification] and
+ * [zoneValues], then runs [body] in that zone and returns the result.
+ *
+ * The [onError] function is used *both* to handle asynchronous errors
+ * by overriding [ZoneSpecification.handleUncaughtError] in [zoneSpecification],
+ * if any, *and* to handle errors thrown synchronously by the call to [body].
+ *
+ * If an error occurs synchronously in [body],
+ * then throwing in the [onError] handler
+ * makes the call to `runZonedGuarded` throw that error,
+ * and otherwise the call to `runZonedGuarded` returns `null`.
+ *
+ * If the zone specification has a `handleUncaughtError` value or the [onError]
+ * parameter is provided, the zone becomes an error-zone.
+ *
+ * Errors will never cross error-zone boundaries by themselves.
+ * Errors that try to cross error-zone boundaries are considered uncaught in
+ * their originating error zone.
+ *
+ *     var future = new Future.value(499);
+ *     runZoned(() {
+ *       var future2 = future.then((_) { throw "error in first error-zone"; });
+ *       runZoned(() {
+ *         var future3 = future2.catchError((e) { print("Never reached!"); });
+ *       }, onError: (e, s) { print("unused error handler"); });
+ *     }, onError: (e, s) { print("catches error of first error-zone."); });
+ *
+ * Example:
+ *
+ *     runZoned(() {
+ *       new Future(() { throw "asynchronous error"; });
+ *     }, onError: (e, s) => print(e));  // Will print "asynchronous error".
+ *
+ * It is possible to manually pass an error from one error zone to another
+ * by re-throwing it in the new zone. If [onError] throws, that error will
+ * occur in the original zone where [runZoned] was called.
+ */
+@Since("2.8")
+R runZonedGuarded<R>(R body(), void onError(Object error, StackTrace stack),
+    {Map zoneValues, ZoneSpecification zoneSpecification}) {
+  ArgumentError.checkNotNull(body, "body");
+  ArgumentError.checkNotNull(onError, "onError");
+
   HandleUncaughtErrorHandler errorHandler = (Zone self, ZoneDelegate parent,
       Zone zone, error, StackTrace stackTrace) {
     try {
-      if (binaryOnError != null) {
-        self.parent.runBinary(binaryOnError, error, stackTrace);
-      } else {
-        assert(unaryOnError != null);
-        self.parent.runUnary(unaryOnError, error);
-      }
+      self.parent.runBinary(onError, error, stackTrace);
     } catch (e, s) {
       if (identical(e, error)) {
         parent.handleUncaughtError(zone, error, stackTrace);
@@ -1521,13 +1569,8 @@ R runZoned<R>(R body(),
   }
   try {
     return _runZoned<R>(body, zoneValues, zoneSpecification);
-  } catch (e, stackTrace) {
-    if (binaryOnError != null) {
-      binaryOnError(e, stackTrace);
-    } else {
-      assert(unaryOnError != null);
-      unaryOnError(e);
-    }
+  } catch (error, stackTrace) {
+    onError(error, stackTrace);
   }
   return null;
 }
diff --git a/sdk/lib/io/overrides.dart b/sdk/lib/io/overrides.dart
index 0692f9d9f0b..eecda8eb0be 100644
--- a/sdk/lib/io/overrides.dart
+++ b/sdk/lib/io/overrides.dart
@@ -92,11 +92,7 @@ abstract class IOOverrides {
       // ServerSocket
       Future<ServerSocket> Function(dynamic, int,
               {int backlog, bool v6Only, bool shared})
-          serverSocketBind,
-
-      // Optional Zone parameters
-      ZoneSpecification zoneSpecification,
-      Function onError}) {
+          serverSocketBind}) {
     IOOverrides overrides = new _IOOverridesScope(
       // Directory
       createDirectory,
@@ -131,22 +127,15 @@ abstract class IOOverrides {
       // ServerSocket
       serverSocketBind,
     );
-    return _asyncRunZoned<R>(body,
-        zoneValues: {_ioOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+    return _asyncRunZoned<R>(body, zoneValues: {_ioOverridesToken: overrides});
   }
 
   /// Runs [body] in a fresh [Zone] using the overrides found in [overrides].
   ///
   /// Note that [overrides] should be an instance of a class that extends
   /// [IOOverrides].
-  static R runWithIOOverrides<R>(R body(), IOOverrides overrides,
-      {ZoneSpecification zoneSpecification, Function onError}) {
-    return _asyncRunZoned<R>(body,
-        zoneValues: {_ioOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+  static R runWithIOOverrides<R>(R body(), IOOverrides overrides) {
+    return _asyncRunZoned<R>(body, zoneValues: {_ioOverridesToken: overrides});
   }
 
   // Directory
diff --git a/sdk_nnbd/lib/_http/overrides.dart b/sdk_nnbd/lib/_http/overrides.dart
index be658c1e0a1..bbd21eef792 100644
--- a/sdk_nnbd/lib/_http/overrides.dart
+++ b/sdk_nnbd/lib/_http/overrides.dart
@@ -49,27 +49,20 @@ abstract class HttpOverrides {
   static R runZoned<R>(R body(),
       {HttpClient Function(SecurityContext?)? createHttpClient,
       String Function(Uri uri, Map<String, String>? environment)?
-          findProxyFromEnvironment,
-      ZoneSpecification? zoneSpecification,
-      Function? onError}) {
+          findProxyFromEnvironment}) {
     HttpOverrides overrides =
         new _HttpOverridesScope(createHttpClient, findProxyFromEnvironment);
     return _asyncRunZoned<R>(body,
-        zoneValues: {_httpOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+        zoneValues: {_httpOverridesToken: overrides});
   }
 
   /// Runs [body] in a fresh [Zone] using the overrides found in [overrides].
   ///
   /// Note that [overrides] should be an instance of a class that extends
   /// [HttpOverrides].
-  static R runWithHttpOverrides<R>(R body(), HttpOverrides overrides,
-      {ZoneSpecification? zoneSpecification, Function? onError}) {
+  static R runWithHttpOverrides<R>(R body(), HttpOverrides overrides) {
     return _asyncRunZoned<R>(body,
-        zoneValues: {_httpOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+        zoneValues: {_httpOverridesToken: overrides});
   }
 
   /// Returns a new [HttpClient] using the given [context].
diff --git a/sdk_nnbd/lib/async/zone.dart b/sdk_nnbd/lib/async/zone.dart
index 53ad1669a0b..3c50e19d546 100644
--- a/sdk_nnbd/lib/async/zone.dart
+++ b/sdk_nnbd/lib/async/zone.dart
@@ -1465,7 +1465,7 @@ const _Zone _rootZone = const _RootZone();
  * If an error occurs synchronously in [body],
  * then throwing in the [onError] handler
  * makes the call to `runZone` throw that error,
- * and otherwise the call to `runZoned` returns `null`.
+ * and otherwise the call to `runZoned` attempt to return `null`.
  *
  * If the zone specification has a `handleUncaughtError` value or the [onError]
  * parameter is provided, the zone becomes an error-zone.
@@ -1474,19 +1474,19 @@ const _Zone _rootZone = const _RootZone();
  * Errors that try to cross error-zone boundaries are considered uncaught in
  * their originating error zone.
  *
- *     var future = Future.value(499);
+ *     var future = new Future.value(499);
  *     runZoned(() {
  *       var future2 = future.then((_) { throw "error in first error-zone"; });
  *       runZoned(() {
  *         var future3 = future2.catchError((e) { print("Never reached!"); });
- *       }, onError: (e) { print("unused error handler"); });
- *     }, onError: (e) { print("catches error of first error-zone."); });
+ *       }, onError: (e, s) { print("unused error handler"); });
+ *     }, onError: (e, s) { print("catches error of first error-zone."); });
  *
  * Example:
  *
  *     runZoned(() {
  *       new Future(() { throw "asynchronous error"; });
- *     }, onError: print);  // Will print "asynchronous error".
+ *     }, onError: (e, s) => print(e));  // Will print "asynchronous error".
  *
  * It is possible to manually pass an error from one error zone to another
  * by re-throwing it in the new zone. If [onError] throws, that error will
@@ -1495,30 +1495,74 @@ const _Zone _rootZone = const _RootZone();
 R runZoned<R>(R body(),
     {Map<Object?, Object?>? zoneValues,
     ZoneSpecification? zoneSpecification,
-    Function? onError}) {
-  if (onError == null) {
-    return _runZoned<R>(body, zoneValues, zoneSpecification);
-  }
-  void Function(Object)? unaryOnError;
-  void Function(Object, StackTrace)? binaryOnError;
-  if (onError is void Function(Object, StackTrace)) {
-    binaryOnError = onError;
-  } else if (onError is void Function(Object)) {
-    unaryOnError = onError;
-  } else {
-    throw new ArgumentError("onError callback must take either an Object "
-        "(the error), or both an Object (the error) and a StackTrace.");
+    @Deprecated("Use runZonedGuarded instead") Function? onError}) {
+  ArgumentError.checkNotNull(body, "body");
+  if (onError != null) {
+    // TODO: Remove this when code have been migrated off using [onError].
+    if (onError is! void Function(Object, StackTrace)) {
+      if (onError is void Function(Object)) {
+        var originalOnError = onError;
+        onError = (Object error, StackTrace stack) => originalOnError(error);
+      } else {
+        throw ArgumentError.value(onError, "onError",
+            "Must be Function(Object) or Function(Object, StackTrace)");
+      }
+    }
+    return runZonedGuarded(body, onError,
+        zoneSpecification: zoneSpecification, zoneValues: zoneValues) as R;
   }
+  return _runZoned<R>(body, zoneValues, zoneSpecification);
+}
+
+/**
+ * Runs [body] in its own error zone.
+ *
+ * Creates a new zone using [Zone.fork] based on [zoneSpecification] and
+ * [zoneValues], then runs [body] in that zone and returns the result.
+ *
+ * The [onError] function is used *both* to handle asynchronous errors
+ * by overriding [ZoneSpecification.handleUncaughtError] in [zoneSpecification],
+ * if any, *and* to handle errors thrown synchronously by the call to [body].
+ *
+ * If an error occurs synchronously in [body],
+ * then throwing in the [onError] handler
+ * makes the call to `runZonedGuarded` throw that error,
+ * and otherwise the call to `runZonedGuarded` returns `null`.
+ *
+ * The zone will always be an error-zone.
+ *
+ * Errors will never cross error-zone boundaries by themselves.
+ * Errors that try to cross error-zone boundaries are considered uncaught in
+ * their originating error zone.
+ * ```dart
+ * var future = Future.value(499);
+ * runZonedGuarded(() {
+ *   var future2 = future.then((_) { throw "error in first error-zone"; });
+ *   runZonedGuarded(() {
+ *     var future3 = future2.catchError((e) { print("Never reached!"); });
+ *   }, (e, s) { print("unused error handler"); });
+ * }, (e, s) { print("catches error of first error-zone."); });
+ * ```
+ * Example:
+ * ```dart
+ * runZonedGuarded(() {
+ *   new Future(() { throw "asynchronous error"; });
+ * }, (e, s) => print(e));  // Will print "asynchronous error".
+ * ```
+ * It is possible to manually pass an error from one error zone to another
+ * by re-throwing it in the new zone. If [onError] throws, that error will
+ * occur in the original zone where [runZoned] was called.
+ */
+@Since("2.8")
+R? runZonedGuarded<R>(R body(), void onError(Object error, StackTrace stack),
+    {Map<Object?, Object?>? zoneValues, ZoneSpecification? zoneSpecification}) {
+  ArgumentError.checkNotNull(body, "body");
+  ArgumentError.checkNotNull(onError, "onError");
   _Zone parentZone = Zone._current;
   HandleUncaughtErrorHandler errorHandler = (Zone self, ZoneDelegate parent,
       Zone zone, Object error, StackTrace stackTrace) {
     try {
-      if (binaryOnError != null) {
-        parentZone.runBinary(binaryOnError, error, stackTrace);
-      } else {
-        assert(unaryOnError != null);
-        parentZone.runUnary(unaryOnError!, error);
-      }
+      parentZone.runBinary(onError, error, stackTrace);
     } catch (e, s) {
       if (identical(e, error)) {
         parent.handleUncaughtError(zone, error, stackTrace);
@@ -1536,17 +1580,10 @@ R runZoned<R>(R body(),
   }
   try {
     return _runZoned<R>(body, zoneValues, zoneSpecification);
-  } catch (e, stackTrace) {
-    if (binaryOnError != null) {
-      binaryOnError(e, stackTrace);
-    } else {
-      assert(unaryOnError != null);
-      unaryOnError!(e);
-    }
+  } catch (error, stackTrace) {
+    onError(error, stackTrace);
   }
-  // TODO(lrn): Change behavior to throw the actual resulting error,
-  // perhaps even synchronously.
-  return null as R;
+  return null;
 }
 
 /// Runs [body] in a new zone based on [zoneValues] and [specification].
diff --git a/sdk_nnbd/lib/io/overrides.dart b/sdk_nnbd/lib/io/overrides.dart
index 1fd0f064d27..4b7deaaa8d2 100644
--- a/sdk_nnbd/lib/io/overrides.dart
+++ b/sdk_nnbd/lib/io/overrides.dart
@@ -90,11 +90,7 @@ abstract class IOOverrides {
       // ServerSocket
       Future<ServerSocket> Function(dynamic, int,
               {int backlog, bool v6Only, bool shared})?
-          serverSocketBind,
-
-      // Optional Zone parameters
-      ZoneSpecification? zoneSpecification,
-      Function? onError}) {
+          serverSocketBind}) {
     IOOverrides overrides = new _IOOverridesScope(
       // Directory
       createDirectory,
@@ -129,22 +125,15 @@ abstract class IOOverrides {
       // ServerSocket
       serverSocketBind,
     );
-    return _asyncRunZoned<R>(body,
-        zoneValues: {_ioOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+    return _asyncRunZoned<R>(body, zoneValues: {_ioOverridesToken: overrides});
   }
 
   /// Runs [body] in a fresh [Zone] using the overrides found in [overrides].
   ///
   /// Note that [overrides] should be an instance of a class that extends
   /// [IOOverrides].
-  static R runWithIOOverrides<R>(R body(), IOOverrides overrides,
-      {ZoneSpecification? zoneSpecification, Function? onError}) {
-    return _asyncRunZoned<R>(body,
-        zoneValues: {_ioOverridesToken: overrides},
-        zoneSpecification: zoneSpecification,
-        onError: onError);
+  static R runWithIOOverrides<R>(R body(), IOOverrides overrides) {
+    return _asyncRunZoned<R>(body, zoneValues: {_ioOverridesToken: overrides});
   }
 
   // Directory
diff --git a/tests/lib/async/catch_errors.dart b/tests/lib/async/catch_errors.dart
index c684cf93920..ff9260d0a01 100644
--- a/tests/lib/async/catch_errors.dart
+++ b/tests/lib/async/catch_errors.dart
@@ -11,7 +11,7 @@ Stream catchErrors(dynamic body()) {
   }
 
   void onListen() {
-    runZoned(body, onError: onError);
+    runZonedGuarded(body, onError);
   }
 
   controller = new StreamController(onListen: onListen);
@@ -21,7 +21,7 @@ Stream catchErrors(dynamic body()) {
 runZonedScheduleMicrotask(body(),
     {void onScheduleMicrotask(void callback()), Function? onError}) {
   if (onScheduleMicrotask == null) {
-    return runZoned(body, onError: onError);
+    return runZonedGuarded(body, onError);
   }
   HandleUncaughtErrorHandler errorHandler;
   if (onError != null) {
diff --git a/tests/lib/async/future_test.dart b/tests/lib/async/future_test.dart
index 790b1bd39ed..c38da0f6bf3 100644
--- a/tests/lib/async/future_test.dart
+++ b/tests/lib/async/future_test.dart
@@ -868,7 +868,7 @@ void testWaitCleanUpError() {
   asyncStart();
   asyncStart();
   asyncStart();
-  runZoned(() {
+  runZonedGuarded(() {
     Future.wait([
       new Future.delayed(cms, () => 0),
       new Future.delayed(cms * 2, () => throw 1),
@@ -882,7 +882,7 @@ void testWaitCleanUpError() {
       Expect.equals(e, 1);
       asyncEnd();
     });
-  }, onError: (e, s) {
+  }, (e, s) {
     int index = e;
     Expect.isTrue(index == 0 || index == 2, "$index");
     Expect.isFalse(uncaughts[index]);
diff --git a/tests/lib/async/run_zoned4_test.dart b/tests/lib/async/run_zoned4_test.dart
index 9df955e201a..fb5166ab7ad 100644
--- a/tests/lib/async/run_zoned4_test.dart
+++ b/tests/lib/async/run_zoned4_test.dart
@@ -10,7 +10,7 @@ main() {
   // error handler is defined.
   Expect.equals(
       499,
-      runZoned(() => 499, onError: (e) {
+      runZonedGuarded(() => 499, (e, s) {
         throw "Unexpected";
       }));
 }
diff --git a/tests/lib/async/run_zoned5_test.dart b/tests/lib/async/run_zoned5_test.dart
index 7a7da9e9cce..0787fd569f5 100644
--- a/tests/lib/async/run_zoned5_test.dart
+++ b/tests/lib/async/run_zoned5_test.dart
@@ -9,9 +9,9 @@ import 'dart:async';
 main() {
   asyncStart();
   // Ensure that `runZoned`'s onError handles synchronous errors.
-  runZoned(() {
+  runZonedGuarded(() {
     throw 0;
-  }, onError: (e) {
+  }, (e, s) {
     Expect.equals(0, e);
     asyncEnd();
   });
diff --git a/tests/lib/async/run_zoned6_test.dart b/tests/lib/async/run_zoned6_test.dart
index 906c776f3d6..837e6f19ecd 100644
--- a/tests/lib/async/run_zoned6_test.dart
+++ b/tests/lib/async/run_zoned6_test.dart
@@ -12,9 +12,9 @@ main() {
   // in the error handler at that point (when it is a synchronous error) yields
   // a synchronous error.
   try {
-    runZoned(() {
+    runZonedGuarded(() {
       throw 0;
-    }, onError: (e) {
+    }, (e, s) {
       Expect.equals(0, e);
       throw e;  //#01 : ok
       asyncEnd();
diff --git a/tests/lib/async/run_zoned8_test.dart b/tests/lib/async/run_zoned8_test.dart
index fca39896f95..9a6b917aea6 100644
--- a/tests/lib/async/run_zoned8_test.dart
+++ b/tests/lib/async/run_zoned8_test.dart
@@ -13,7 +13,7 @@ main() {
 
   var events = [];
   // Test runZoned with periodic Timers.
-  runZoned(() {
+  runZonedGuarded(() {
     int counter = 0;
     new Timer.periodic(const Duration(milliseconds: 50), (timer) {
       if (counter == 1) {
@@ -24,7 +24,7 @@ main() {
       events.add(counter);
       throw counter;
     });
-  }, onError: (e, [s]) {
+  }, (e, [s]) {
     events.add("error: $e");
     Expect.isNotNull(s); // Regression test for http://dartbug.com/33589
   });
diff --git a/tests/lib/async/run_zoned9_test.dart b/tests/lib/async/run_zoned9_test.dart
index 1ab97953cdb..a42b8df5e0d 100644
--- a/tests/lib/async/run_zoned9_test.dart
+++ b/tests/lib/async/run_zoned9_test.dart
@@ -12,15 +12,15 @@ main() {
   // to the next runZoned when the handler returns false.
   bool sawInnerHandler = false;
   try {
-    runZoned(() {
+    runZonedGuarded(() {
       runZoned(() {
         throw 0;
-      }, onError: (e) {
+      }, onError: (e, s) {
         Expect.equals(0, e);
         sawInnerHandler = true;
         throw e;
       });
-    }, onError: (e) {
+    }, (e, s) {
       Expect.equals(0, e);
       Expect.isTrue(sawInnerHandler);
       // If we are waiting for an error, don't asyncEnd, but let it time out.
diff --git a/tests/lib/async/stream_event_transformed_test.dart b/tests/lib/async/stream_event_transformed_test.dart
index a132aad9ce2..73de60eef4a 100644
--- a/tests/lib/async/stream_event_transformed_test.dart
+++ b/tests/lib/async/stream_event_transformed_test.dart
@@ -267,7 +267,7 @@ main() {
 
     bool streamIsDone = false;
     int errorCount = 0;
-    runZoned(() {
+    runZonedGuarded(() {
       controller.stream
           .transform(new SinkTransformer((sink) =>
               new FutureWaitingTransformerSink(sink, closeCompleter.future)))
@@ -280,7 +280,7 @@ main() {
         Expect.listEquals([], events);
         streamIsDone = true;
       });
-    }, onError: (e) {
+    }, (e, s) {
       Expect.isTrue(e is StateError);
       errorCount++;
     });
diff --git a/tests/lib/async/stream_subscription_as_future_test.dart b/tests/lib/async/stream_subscription_as_future_test.dart
index d12c0acafc1..48309e33cf6 100644
--- a/tests/lib/async/stream_subscription_as_future_test.dart
+++ b/tests/lib/async/stream_subscription_as_future_test.dart
@@ -114,7 +114,7 @@ main() {
   });
 
   test("subscription.asFuture failure in cancel", () {
-    runZoned(() {
+    runZonedGuarded(() {
       var completer = new Completer();
       var controller =
           new StreamController(onCancel: () => completer.future, sync: true);
@@ -135,7 +135,7 @@ main() {
         Expect.isFalse(catchErrorHasRun);
         completer.completeError(499);
       }));
-    }, onError: expectAsync((e) {
+    }, expectAsync2((e, s) {
       Expect.equals(499, e);
     }));
   });
diff --git a/tests/lib/async/stream_zones_test.dart b/tests/lib/async/stream_zones_test.dart
index 6d4582e36fb..3a41e1298ab 100644
--- a/tests/lib/async/stream_zones_test.dart
+++ b/tests/lib/async/stream_zones_test.dart
@@ -10,8 +10,8 @@ import 'dart:async';
 test1() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
-    runZoned(() {
+  runZonedGuarded(() {
+    runZonedGuarded(() {
       var c = new StreamController();
       c.stream.listen((x) => events.add("stream: $x"),
           onError: (x) => events.add("stream: error $x"),
@@ -19,8 +19,8 @@ test1() {
       c.add(1);
       c.addError(2);
       c.close();
-    }, onError: (x) => events.add("rza: error $x"));
-  }, onError: (x) => events.add("rzb: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -33,18 +33,18 @@ test1() {
 test2() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c;
-    runZoned(() {
+    runZonedGuarded(() {
       c = new StreamController();
       c.stream.listen((x) => events.add("stream: $x"),
           onError: (x) => events.add("stream: error $x"),
           onDone: done.complete);
-    }, onError: (x) => events.add("rza: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
     c.add(1);
     c.addError(2);
     c.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -57,16 +57,16 @@ test2() {
 test3() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-    runZoned(() {
+    runZonedGuarded(() {
       c.add(1);
       c.addError(2);
       c.close();
-    }, onError: (x) => events.add("rza: error $x"));
-  }, onError: (x) => events.add("rzb: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -79,18 +79,18 @@ test3() {
 test4() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-    runZoned(() {
+    runZonedGuarded(() {
       var c2 = new StreamController();
       c.addStream(c2.stream).whenComplete(c.close);
       c2.add(1);
       c2.addError(2);
       c2.close();
-    }, onError: (x) => events.add("rza: error $x"));
-  }, onError: (x) => events.add("rzb: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -104,20 +104,20 @@ test4() {
 test5() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c;
-    runZoned(() {
+    runZonedGuarded(() {
       c = new StreamController();
       c.stream.listen((x) => events.add("stream: $x"),
           onError: (x) => events.add("stream: error $x"),
           onDone: done.complete);
-    }, onError: (x) => events.add("rza: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
     var c2 = new StreamController();
     c.addStream(c2.stream).whenComplete(c.close);
     c2.add(1);
     c2.addError(2);
     c2.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -130,18 +130,18 @@ test6() {
   var events = [];
   var done = new Completer();
   var c;
-  runZoned(() {
+  runZonedGuarded(() {
     c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-  }, onError: (x) => events.add("rza: error $x"));
-  runZoned(() {
+  }, (e, s) => events.add("rza: error $e"));
+  runZonedGuarded(() {
     var c2 = new StreamController();
     c.addStream(c2.stream).whenComplete(c.close);
     c2.add(1);
     c2.addError(2);
     c2.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e, s"));
   return [
     done.future,
     () {
@@ -155,16 +155,16 @@ test7() {
   var events = [];
   var done = new Completer();
   var c;
-  runZoned(() {
+  runZonedGuarded(() {
     c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-  }, onError: (x) => events.add("rza: error $x"));
-  runZoned(() {
+  }, (e, s) => events.add("rza: error $e"));
+  runZonedGuarded(() {
     c.add(1);
     c.addError(2);
     c.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
diff --git a/tests/lib_2/async/run_zoned4_test.dart b/tests/lib_2/async/run_zoned4_test.dart
index 9df955e201a..fb5166ab7ad 100644
--- a/tests/lib_2/async/run_zoned4_test.dart
+++ b/tests/lib_2/async/run_zoned4_test.dart
@@ -10,7 +10,7 @@ main() {
   // error handler is defined.
   Expect.equals(
       499,
-      runZoned(() => 499, onError: (e) {
+      runZonedGuarded(() => 499, (e, s) {
         throw "Unexpected";
       }));
 }
diff --git a/tests/lib_2/async/run_zoned5_test.dart b/tests/lib_2/async/run_zoned5_test.dart
index 7a7da9e9cce..0787fd569f5 100644
--- a/tests/lib_2/async/run_zoned5_test.dart
+++ b/tests/lib_2/async/run_zoned5_test.dart
@@ -9,9 +9,9 @@ import 'dart:async';
 main() {
   asyncStart();
   // Ensure that `runZoned`'s onError handles synchronous errors.
-  runZoned(() {
+  runZonedGuarded(() {
     throw 0;
-  }, onError: (e) {
+  }, (e, s) {
     Expect.equals(0, e);
     asyncEnd();
   });
diff --git a/tests/lib_2/async/run_zoned6_test.dart b/tests/lib_2/async/run_zoned6_test.dart
index 906c776f3d6..837e6f19ecd 100644
--- a/tests/lib_2/async/run_zoned6_test.dart
+++ b/tests/lib_2/async/run_zoned6_test.dart
@@ -12,9 +12,9 @@ main() {
   // in the error handler at that point (when it is a synchronous error) yields
   // a synchronous error.
   try {
-    runZoned(() {
+    runZonedGuarded(() {
       throw 0;
-    }, onError: (e) {
+    }, (e, s) {
       Expect.equals(0, e);
       throw e;  //#01 : ok
       asyncEnd();
diff --git a/tests/lib_2/async/run_zoned9_test.dart b/tests/lib_2/async/run_zoned9_test.dart
index 1ab97953cdb..be96ac80a50 100644
--- a/tests/lib_2/async/run_zoned9_test.dart
+++ b/tests/lib_2/async/run_zoned9_test.dart
@@ -12,15 +12,15 @@ main() {
   // to the next runZoned when the handler returns false.
   bool sawInnerHandler = false;
   try {
-    runZoned(() {
-      runZoned(() {
+    runZonedGuarded(() {
+      runZonedGuarded(() {
         throw 0;
-      }, onError: (e) {
+      }, (e, s) {
         Expect.equals(0, e);
         sawInnerHandler = true;
         throw e;
       });
-    }, onError: (e) {
+    }, (e, s) {
       Expect.equals(0, e);
       Expect.isTrue(sawInnerHandler);
       // If we are waiting for an error, don't asyncEnd, but let it time out.
diff --git a/tests/lib_2/async/stream_event_transformed_test.dart b/tests/lib_2/async/stream_event_transformed_test.dart
index 2a056832e29..2b22fad7aeb 100644
--- a/tests/lib_2/async/stream_event_transformed_test.dart
+++ b/tests/lib_2/async/stream_event_transformed_test.dart
@@ -267,7 +267,7 @@ main() {
 
     bool streamIsDone = false;
     int errorCount = 0;
-    runZoned(() {
+    runZonedGuarded(() {
       controller.stream
           .transform(new SinkTransformer((sink) =>
               new FutureWaitingTransformerSink(sink, closeCompleter.future)))
@@ -280,7 +280,7 @@ main() {
         Expect.listEquals([], events);
         streamIsDone = true;
       });
-    }, onError: (e) {
+    }, (e, s) {
       Expect.isTrue(e is StateError);
       errorCount++;
     });
diff --git a/tests/lib_2/async/stream_subscription_as_future_test.dart b/tests/lib_2/async/stream_subscription_as_future_test.dart
index 5be5c91d2a8..55f2c290438 100644
--- a/tests/lib_2/async/stream_subscription_as_future_test.dart
+++ b/tests/lib_2/async/stream_subscription_as_future_test.dart
@@ -114,7 +114,7 @@ main() {
   });
 
   test("subscription.asFuture failure in cancel", () {
-    runZoned(() {
+    runZonedGuarded(() {
       var completer = new Completer();
       var controller =
           new StreamController(onCancel: () => completer.future, sync: true);
@@ -135,7 +135,7 @@ main() {
         Expect.isFalse(catchErrorHasRun);
         completer.completeError(499);
       }));
-    }, onError: expectAsync((e) {
+    }, expectAsync2((e, s) {
       Expect.equals(499, e);
     }));
   });
diff --git a/tests/lib_2/async/stream_zones_test.dart b/tests/lib_2/async/stream_zones_test.dart
index 6d4582e36fb..9f382ba77df 100644
--- a/tests/lib_2/async/stream_zones_test.dart
+++ b/tests/lib_2/async/stream_zones_test.dart
@@ -10,8 +10,8 @@ import 'dart:async';
 test1() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
-    runZoned(() {
+  runZonedGuarded(() {
+    runZonedGuarded(() {
       var c = new StreamController();
       c.stream.listen((x) => events.add("stream: $x"),
           onError: (x) => events.add("stream: error $x"),
@@ -19,8 +19,8 @@ test1() {
       c.add(1);
       c.addError(2);
       c.close();
-    }, onError: (x) => events.add("rza: error $x"));
-  }, onError: (x) => events.add("rzb: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -33,18 +33,18 @@ test1() {
 test2() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c;
-    runZoned(() {
+    runZonedGuarded(() {
       c = new StreamController();
       c.stream.listen((x) => events.add("stream: $x"),
           onError: (x) => events.add("stream: error $x"),
           onDone: done.complete);
-    }, onError: (x) => events.add("rza: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
     c.add(1);
     c.addError(2);
     c.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -57,16 +57,16 @@ test2() {
 test3() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-    runZoned(() {
+    runZonedGuarded(() {
       c.add(1);
       c.addError(2);
       c.close();
-    }, onError: (x) => events.add("rza: error $x"));
-  }, onError: (x) => events.add("rzb: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -79,18 +79,18 @@ test3() {
 test4() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-    runZoned(() {
+    runZonedGuarded(() {
       var c2 = new StreamController();
       c.addStream(c2.stream).whenComplete(c.close);
       c2.add(1);
       c2.addError(2);
       c2.close();
-    }, onError: (x) => events.add("rza: error $x"));
-  }, onError: (x) => events.add("rzb: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -104,20 +104,20 @@ test4() {
 test5() {
   var events = [];
   var done = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     var c;
-    runZoned(() {
+    runZonedGuarded(() {
       c = new StreamController();
       c.stream.listen((x) => events.add("stream: $x"),
           onError: (x) => events.add("stream: error $x"),
           onDone: done.complete);
-    }, onError: (x) => events.add("rza: error $x"));
+    }, (e, s) => events.add("rza: error $e"));
     var c2 = new StreamController();
     c.addStream(c2.stream).whenComplete(c.close);
     c2.add(1);
     c2.addError(2);
     c2.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -130,18 +130,18 @@ test6() {
   var events = [];
   var done = new Completer();
   var c;
-  runZoned(() {
+  runZonedGuarded(() {
     c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-  }, onError: (x) => events.add("rza: error $x"));
-  runZoned(() {
+  }, (e, s) => events.add("rza: error $e"));
+  runZonedGuarded(() {
     var c2 = new StreamController();
     c.addStream(c2.stream).whenComplete(c.close);
     c2.add(1);
     c2.addError(2);
     c2.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
@@ -155,16 +155,16 @@ test7() {
   var events = [];
   var done = new Completer();
   var c;
-  runZoned(() {
+  runZonedGuarded(() {
     c = new StreamController();
     c.stream.listen((x) => events.add("stream: $x"),
         onError: (x) => events.add("stream: error $x"), onDone: done.complete);
-  }, onError: (x) => events.add("rza: error $x"));
-  runZoned(() {
+  }, (e, s) => events.add("rza: error $e"));
+  runZonedGuarded(() {
     c.add(1);
     c.addError(2);
     c.close();
-  }, onError: (x) => events.add("rzb: error $x"));
+  }, (e, s) => events.add("rzb: error $e"));
   return [
     done.future,
     () {
diff --git a/tests/standalone/io/async_catch_errors_test.dart b/tests/standalone/io/async_catch_errors_test.dart
index 431057b3914..c039ad83c2e 100644
--- a/tests/standalone/io/async_catch_errors_test.dart
+++ b/tests/standalone/io/async_catch_errors_test.dart
@@ -12,11 +12,11 @@ var events = [];
 
 Future testSocketException() {
   var completer = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     Socket.connect("4", 1).then((Socket s) {
       Expect.fail("Socket should not be able to connect");
     });
-  }, onError: (err) {
+  }, (err, s) {
     if (err is! SocketException) Expect.fail("Not expected error: $err");
     completer.complete("socket test, ok.");
     events.add("SocketException");
@@ -26,9 +26,9 @@ Future testSocketException() {
 
 Future testFileSystemException() {
   var completer = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     new File("lol it's not a file\n").openRead().listen(null);
-  }, onError: (err) {
+  }, (err, s) {
     if (err is! FileSystemException) Expect.fail("Not expected error: $err");
     completer.complete("file test, ok.");
     events.add("FileSystemException");
diff --git a/tests/standalone/io/file_system_watcher_test.dart b/tests/standalone/io/file_system_watcher_test.dart
index 3ef4175e318..7714f382ee9 100644
--- a/tests/standalone/io/file_system_watcher_test.dart
+++ b/tests/standalone/io/file_system_watcher_test.dart
@@ -452,11 +452,11 @@ testWatchOverflow() async {
 }
 
 void watcher(SendPort sendPort) async {
-  runZoned(() {
+  runZonedGuarded(() {
     var watcher = Directory.systemTemp.watch(recursive: true);
     watcher.listen((data) async {});
     sendPort.send('start');
-  }, onError: (error) {
+  }, (error, stack) {
     print(error);
     sendPort.send('end');
   });
diff --git a/tests/standalone/io/http_server_test.dart b/tests/standalone/io/http_server_test.dart
index 911d7bf9a40..3351df73045 100644
--- a/tests/standalone/io/http_server_test.dart
+++ b/tests/standalone/io/http_server_test.dart
@@ -159,7 +159,7 @@ void testHttpServerZone() {
 void testHttpServerZoneError() {
   asyncStart();
   Expect.equals(Zone.root, Zone.current);
-  runZoned(() {
+  runZonedGuarded(() {
     Expect.notEquals(Zone.root, Zone.current);
     HttpServer.bind("127.0.0.1", 0).then((server) {
       Expect.notEquals(Zone.root, Zone.current);
@@ -178,14 +178,14 @@ void testHttpServerZoneError() {
         socket.listen(null);
       });
     });
-  }, onError: (e) {
+  }, (e, s) {
     asyncEnd();
   });
 }
 
 void testHttpServerClientClose() {
   HttpServer.bind("127.0.0.1", 0).then((server) {
-    runZoned(() {
+    runZonedGuarded(() {
       server.listen((request) {
         request.response.bufferOutput = false;
         request.response.add(new Uint8List(64 * 1024));
@@ -195,7 +195,7 @@ void testHttpServerClientClose() {
           });
         });
       });
-    }, onError: (e, s) {
+    }, (e, s) {
       Expect.fail("Unexpected error: $e(${e.hashCode})\n$s");
     });
     var client = new HttpClient();
diff --git a/tests/standalone/io/raw_socket_test.dart b/tests/standalone/io/raw_socket_test.dart
index 8280094ebd8..935db3738b0 100644
--- a/tests/standalone/io/raw_socket_test.dart
+++ b/tests/standalone/io/raw_socket_test.dart
@@ -426,7 +426,7 @@ void testSocketZone() {
 void testSocketZoneError() {
   asyncStart();
   Expect.equals(Zone.root, Zone.current);
-  runZoned(() {
+  runZonedGuarded(() {
     Expect.notEquals(Zone.root, Zone.current);
     RawServerSocket.bind(InternetAddress.loopbackIPv4, 0).then((server) {
       Expect.notEquals(Zone.root, Zone.current);
@@ -451,7 +451,7 @@ void testSocketZoneError() {
         socket.close();
       });
     });
-  }, onError: (e) {
+  }, (e, s) {
     asyncEnd();
   });
 }
diff --git a/tests/standalone/io/wait_for_event_zone_caught_error_test.dart b/tests/standalone/io/wait_for_event_zone_caught_error_test.dart
index 09e60c47bbf..90484e033e5 100644
--- a/tests/standalone/io/wait_for_event_zone_caught_error_test.dart
+++ b/tests/standalone/io/wait_for_event_zone_caught_error_test.dart
@@ -17,12 +17,12 @@ main() {
   initWaitForEvent();
   asyncStart();
   bool flag = false;
-  runZoned(() {
+  runZonedGuarded(() {
     Timer.run(() {
       asyncEnd();
       throw "Exception";
     });
-  }, onError: (e) {
+  }, (e, s) {
     flag = true;
   });
   Expect.isFalse(flag);
diff --git a/tests/standalone/io/wait_for_exception_test.dart b/tests/standalone/io/wait_for_exception_test.dart
index f5c207d3ae9..6c83553cfb7 100644
--- a/tests/standalone/io/wait_for_exception_test.dart
+++ b/tests/standalone/io/wait_for_exception_test.dart
@@ -11,12 +11,12 @@ import 'package:expect/expect.dart';
 main() {
   asyncStart();
   Completer<bool> c = new Completer<bool>();
-  runZoned(() {
+  runZonedGuarded(() {
     Timer.run(() {
       asyncEnd();
       throw "Error";
     });
-  }, onError: (e) {
+  }, (e, s) {
     Expect.isTrue(e is String);
     c.complete(true);
   });
diff --git a/tests/standalone_2/io/async_catch_errors_test.dart b/tests/standalone_2/io/async_catch_errors_test.dart
index 431057b3914..c039ad83c2e 100644
--- a/tests/standalone_2/io/async_catch_errors_test.dart
+++ b/tests/standalone_2/io/async_catch_errors_test.dart
@@ -12,11 +12,11 @@ var events = [];
 
 Future testSocketException() {
   var completer = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     Socket.connect("4", 1).then((Socket s) {
       Expect.fail("Socket should not be able to connect");
     });
-  }, onError: (err) {
+  }, (err, s) {
     if (err is! SocketException) Expect.fail("Not expected error: $err");
     completer.complete("socket test, ok.");
     events.add("SocketException");
@@ -26,9 +26,9 @@ Future testSocketException() {
 
 Future testFileSystemException() {
   var completer = new Completer();
-  runZoned(() {
+  runZonedGuarded(() {
     new File("lol it's not a file\n").openRead().listen(null);
-  }, onError: (err) {
+  }, (err, s) {
     if (err is! FileSystemException) Expect.fail("Not expected error: $err");
     completer.complete("file test, ok.");
     events.add("FileSystemException");
diff --git a/tests/standalone_2/io/file_system_watcher_test.dart b/tests/standalone_2/io/file_system_watcher_test.dart
index ebb08de244c..d366ff85b46 100644
--- a/tests/standalone_2/io/file_system_watcher_test.dart
+++ b/tests/standalone_2/io/file_system_watcher_test.dart
@@ -451,11 +451,11 @@ testWatchOverflow() async {
 }
 
 void watcher(SendPort sendPort) async {
-  runZoned(() {
+  runZonedGuarded(() {
     var watcher = Directory.systemTemp.watch(recursive: true);
     watcher.listen((data) async {});
     sendPort.send('start');
-  }, onError: (error) {
+  }, (error, stack) {
     print(error);
     sendPort.send('end');
   });
diff --git a/tests/standalone_2/io/http_server_test.dart b/tests/standalone_2/io/http_server_test.dart
index b36fd7e2b42..c9910afaef7 100644
--- a/tests/standalone_2/io/http_server_test.dart
+++ b/tests/standalone_2/io/http_server_test.dart
@@ -159,7 +159,7 @@ void testHttpServerZone() {
 void testHttpServerZoneError() {
   asyncStart();
   Expect.equals(Zone.root, Zone.current);
-  runZoned(() {
+  runZonedGuarded(() {
     Expect.notEquals(Zone.root, Zone.current);
     HttpServer.bind("127.0.0.1", 0).then((server) {
       Expect.notEquals(Zone.root, Zone.current);
@@ -178,14 +178,14 @@ void testHttpServerZoneError() {
         socket.listen(null);
       });
     });
-  }, onError: (e) {
+  }, (e, s) {
     asyncEnd();
   });
 }
 
 void testHttpServerClientClose() {
   HttpServer.bind("127.0.0.1", 0).then((server) {
-    runZoned(() {
+    runZonedGuarded(() {
       server.listen((request) {
         request.response.bufferOutput = false;
         request.response.add(new Uint8List(64 * 1024));
@@ -195,7 +195,7 @@ void testHttpServerClientClose() {
           });
         });
       });
-    }, onError: (e, s) {
+    }, (e, s) {
       Expect.fail("Unexpected error: $e(${e.hashCode})\n$s");
     });
     var client = new HttpClient();
diff --git a/tests/standalone_2/io/raw_socket_test.dart b/tests/standalone_2/io/raw_socket_test.dart
index cf8087de0ca..385b7209f3a 100644
--- a/tests/standalone_2/io/raw_socket_test.dart
+++ b/tests/standalone_2/io/raw_socket_test.dart
@@ -429,7 +429,7 @@ void testSocketZone() {
 void testSocketZoneError() {
   asyncStart();
   Expect.equals(Zone.root, Zone.current);
-  runZoned(() {
+  runZonedGuarded(() {
     Expect.notEquals(Zone.root, Zone.current);
     RawServerSocket.bind(InternetAddress.loopbackIPv4, 0).then((server) {
       Expect.notEquals(Zone.root, Zone.current);
@@ -454,7 +454,7 @@ void testSocketZoneError() {
         socket.close();
       });
     });
-  }, onError: (e) {
+  }, (e, s) {
     asyncEnd();
   });
 }
diff --git a/tests/standalone_2/io/wait_for_event_zone_caught_error_test.dart b/tests/standalone_2/io/wait_for_event_zone_caught_error_test.dart
index 09e60c47bbf..90484e033e5 100644
--- a/tests/standalone_2/io/wait_for_event_zone_caught_error_test.dart
+++ b/tests/standalone_2/io/wait_for_event_zone_caught_error_test.dart
@@ -17,12 +17,12 @@ main() {
   initWaitForEvent();
   asyncStart();
   bool flag = false;
-  runZoned(() {
+  runZonedGuarded(() {
     Timer.run(() {
       asyncEnd();
       throw "Exception";
     });
-  }, onError: (e) {
+  }, (e, s) {
     flag = true;
   });
   Expect.isFalse(flag);
diff --git a/tests/standalone_2/io/wait_for_exception_test.dart b/tests/standalone_2/io/wait_for_exception_test.dart
index f5c207d3ae9..6c83553cfb7 100644
--- a/tests/standalone_2/io/wait_for_exception_test.dart
+++ b/tests/standalone_2/io/wait_for_exception_test.dart
@@ -11,12 +11,12 @@ import 'package:expect/expect.dart';
 main() {
   asyncStart();
   Completer<bool> c = new Completer<bool>();
-  runZoned(() {
+  runZonedGuarded(() {
     Timer.run(() {
       asyncEnd();
       throw "Error";
     });
-  }, onError: (e) {
+  }, (e, s) {
     Expect.isTrue(e is String);
     c.complete(true);
   });