diff --git a/src/vs/workbench/api/electron-browser/mainThreadUrls.ts b/src/vs/workbench/api/electron-browser/mainThreadUrls.ts
index 2eaf1a67e2e..f2ee377a15a 100644
--- a/src/vs/workbench/api/electron-browser/mainThreadUrls.ts
+++ b/src/vs/workbench/api/electron-browser/mainThreadUrls.ts
@@ -24,7 +24,7 @@ class ExtensionUrlHandler implements IURLHandler {
 			return TPromise.as(false);
 		}
 
-		return this.proxy.$handleExternalUri(this.handle, uri).then(() => true);
+		return TPromise.wrap(this.proxy.$handleExternalUri(this.handle, uri)).then(() => true);
 	}
 }
 
diff --git a/src/vs/workbench/api/node/extHost.protocol.ts b/src/vs/workbench/api/node/extHost.protocol.ts
index 8e05d5c666b..53a68deeee4 100644
--- a/src/vs/workbench/api/node/extHost.protocol.ts
+++ b/src/vs/workbench/api/node/extHost.protocol.ts
@@ -466,7 +466,7 @@ export interface MainThreadUrlsShape extends IDisposable {
 }
 
 export interface ExtHostUrlsShape {
-	$handleExternalUri(handle: number, uri: UriComponents): TPromise<void>;
+	$handleExternalUri(handle: number, uri: UriComponents): Thenable<void>;
 }
 
 export interface MainThreadWorkspaceShape extends IDisposable {
diff --git a/src/vs/workbench/api/node/extHostUrls.ts b/src/vs/workbench/api/node/extHostUrls.ts
index b7e4552fc97..f8b7b37f9f4 100644
--- a/src/vs/workbench/api/node/extHostUrls.ts
+++ b/src/vs/workbench/api/node/extHostUrls.ts
@@ -8,7 +8,7 @@ import { MainContext, IMainContext, ExtHostUrlsShape, MainThreadUrlsShape } from
 import { URI, UriComponents } from 'vs/base/common/uri';
 import { TPromise } from 'vs/base/common/winjs.base';
 import { toDisposable } from 'vs/base/common/lifecycle';
-import { asWinJsPromise } from 'vs/base/common/async';
+import { onUnexpectedError } from 'vs/base/common/errors';
 
 export class ExtHostUrls implements ExtHostUrlsShape {
 
@@ -41,14 +41,17 @@ export class ExtHostUrls implements ExtHostUrlsShape {
 		});
 	}
 
-	$handleExternalUri(handle: number, uri: UriComponents): TPromise<void> {
+	$handleExternalUri(handle: number, uri: UriComponents): Thenable<void> {
 		const handler = this.handlers.get(handle);
 
 		if (!handler) {
 			return TPromise.as(null);
 		}
-
-		asWinJsPromise(_ => handler.handleUri(URI.revive(uri)));
+		try {
+			handler.handleUri(URI.revive(uri));
+		} catch (err) {
+			onUnexpectedError(err);
+		}
 
 		return TPromise.as(null);
 	}