diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index 5fd2af1ffd8..29456c89258 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -455,16 +455,12 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 			get terminals() {
 				return extHostTerminalService.terminals;
 			},
-			showTextDocument(documentOrUri: vscode.TextDocument | vscode.Uri, columnOrOptions?: vscode.ViewColumn | vscode.TextDocumentShowOptions, preserveFocus?: boolean): Thenable<vscode.TextEditor> {
-				let documentPromise: Promise<vscode.TextDocument>;
-				if (URI.isUri(documentOrUri)) {
-					documentPromise = Promise.resolve(workspace.openTextDocument(documentOrUri));
-				} else {
-					documentPromise = Promise.resolve(<vscode.TextDocument>documentOrUri);
-				}
-				return documentPromise.then(document => {
-					return extHostEditors.showTextDocument(document, columnOrOptions, preserveFocus);
-				});
+			async showTextDocument(documentOrUri: vscode.TextDocument | vscode.Uri, columnOrOptions?: vscode.ViewColumn | vscode.TextDocumentShowOptions, preserveFocus?: boolean): Promise<vscode.TextEditor> {
+				const document = await (URI.isUri(documentOrUri)
+					? Promise.resolve(workspace.openTextDocument(documentOrUri))
+					: Promise.resolve(<vscode.TextDocument>documentOrUri));
+
+				return extHostEditors.showTextDocument(document, columnOrOptions, preserveFocus);
 			},
 			createTextEditorDecorationType(options: vscode.DecorationRenderOptions): vscode.TextEditorDecorationType {
 				return extHostEditors.createTextEditorDecorationType(options);
diff --git a/src/vs/workbench/api/common/extHostTextEditors.ts b/src/vs/workbench/api/common/extHostTextEditors.ts
index 4a61bf07536..e99f513e940 100644
--- a/src/vs/workbench/api/common/extHostTextEditors.ts
+++ b/src/vs/workbench/api/common/extHostTextEditors.ts
@@ -54,7 +54,7 @@ export class ExtHostEditors implements ExtHostEditorsShape {
 	showTextDocument(document: vscode.TextDocument, column: vscode.ViewColumn, preserveFocus: boolean): Promise<vscode.TextEditor>;
 	showTextDocument(document: vscode.TextDocument, options: { column: vscode.ViewColumn, preserveFocus: boolean, pinned: boolean }): Promise<vscode.TextEditor>;
 	showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions | undefined, preserveFocus?: boolean): Promise<vscode.TextEditor>;
-	showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions | undefined, preserveFocus?: boolean): Promise<vscode.TextEditor> {
+	async showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions | undefined, preserveFocus?: boolean): Promise<vscode.TextEditor> {
 		let options: ITextDocumentShowOptions;
 		if (typeof columnOrOptions === 'number') {
 			options = {
@@ -74,14 +74,18 @@ export class ExtHostEditors implements ExtHostEditorsShape {
 			};
 		}
 
-		return this._proxy.$tryShowTextDocument(document.uri, options).then(id => {
-			const editor = id && this._extHostDocumentsAndEditors.getEditor(id);
-			if (editor) {
-				return editor;
-			} else {
-				throw new Error(`Failed to show text document ${document.uri.toString()}, should show in editor #${id}`);
-			}
-		});
+		const editorId = await this._proxy.$tryShowTextDocument(document.uri, options);
+		const editor = editorId && this._extHostDocumentsAndEditors.getEditor(editorId);
+		if (editor) {
+			return editor;
+		}
+		// we have no editor... having an id means that we had an editor
+		// on the main side and that it isn't the current editor anymore...
+		if (editorId) {
+			throw new Error(`Could NOT open editor for "${document.uri.toString()}" because another editor opened in the meantime.`);
+		} else {
+			throw new Error(`Could NOT open editor for "${document.uri.toString()}".`);
+		}
 	}
 
 	createTextEditorDecorationType(options: vscode.DecorationRenderOptions): vscode.TextEditorDecorationType {