diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index 114996cfc8285e71531710af385826aa70e06912..08bfbe946ed7baacb5edde666de8cb13be46acaa 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -513,7 +513,6 @@
 		"./vs/platform/workspaces/node/workspacesIpc.ts",
 		"./vs/vscode.d.ts",
 		"./vs/vscode.proposed.d.ts",
-		"./vs/workbench/api/browser/viewsContainersExtensionPoint.ts",
 		"./vs/workbench/api/node/extHostExtensionActivator.ts",
 		"./vs/workbench/api/node/extHostSearch.fileIndex.ts",
 		"./vs/workbench/api/node/extHostTypes.ts",
diff --git a/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts b/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts
index 372cacb08fd74038bdf74514ec1f18600402683b..404646c23f57df79e99d5805cb38928b80e39d2b 100644
--- a/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts
+++ b/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts
@@ -124,8 +124,10 @@ export class ActivitybarPart extends Part {
 			const viewContainer = this.getViewContainer(viewlet.id);
 			if (viewContainer) {
 				const viewDescriptors = this.viewsService.getViewDescriptors(viewContainer);
-				this.onDidChangeActiveViews(viewlet, viewDescriptors);
-				viewDescriptors.onDidChangeActiveViews(() => this.onDidChangeActiveViews(viewlet, viewDescriptors));
+				if (viewDescriptors) {
+					this.onDidChangeActiveViews(viewlet, viewDescriptors);
+					viewDescriptors.onDidChangeActiveViews(() => this.onDidChangeActiveViews(viewlet, viewDescriptors));
+				}
 			}
 		}
 		this.saveCachedViewlets();
@@ -145,9 +147,12 @@ export class ActivitybarPart extends Part {
 		this.compositeBar.activateComposite(viewlet.getId());
 		const viewletDescriptor = this.viewletService.getViewlet(viewlet.getId());
 		const viewContainer = this.getViewContainer(viewletDescriptor.id);
-		if (viewContainer && this.viewsService.getViewDescriptors(viewContainer).activeViewDescriptors.length === 0) {
-			// Update the composite bar by hiding
-			this.removeComposite(viewletDescriptor.id, true);
+		if (viewContainer) {
+			const viewDescriptors = this.viewsService.getViewDescriptors(viewContainer);
+			if (viewDescriptors && viewDescriptors.activeViewDescriptors.length === 0) {
+				// Update the composite bar by hiding
+				this.removeComposite(viewletDescriptor.id, true);
+			}
 		}
 	}
 
@@ -396,8 +401,11 @@ export class ActivitybarPart extends Part {
 			if (viewlet) {
 				const views: { when: string }[] = [];
 				if (viewContainer) {
-					for (const { when } of this.viewsService.getViewDescriptors(viewContainer).allViewDescriptors) {
-						views.push({ when: when ? when.serialize() : undefined });
+					const viewDescriptors = this.viewsService.getViewDescriptors(viewContainer);
+					if (viewDescriptors) {
+						for (const { when } of viewDescriptors.allViewDescriptors) {
+							views.push({ when: when ? when.serialize() : undefined });
+						}
 					}
 				}
 				state.push({ id: compositeItem.id, iconUrl: viewlet.iconUrl, views, pinned: compositeItem && compositeItem.pinned, order: compositeItem ? compositeItem.order : undefined, visible: compositeItem && compositeItem.visible });
diff --git a/src/vs/workbench/browser/parts/views/views.ts b/src/vs/workbench/browser/parts/views/views.ts
index b779f81a8d52cb4a8183954dd2e30181c5ec88eb..b1c99bc090acd9fc83ad9e4faf2267412654a243 100644
--- a/src/vs/workbench/browser/parts/views/views.ts
+++ b/src/vs/workbench/browser/parts/views/views.ts
@@ -243,8 +243,10 @@ export class ContributableViewsModel extends Disposable {
 		super();
 		const viewDescriptorCollection = viewsService.getViewDescriptors(container);
 
-		this._register(viewDescriptorCollection.onDidChangeActiveViews(() => this.onDidChangeViewDescriptors(viewDescriptorCollection.activeViewDescriptors)));
-		this.onDidChangeViewDescriptors(viewDescriptorCollection.activeViewDescriptors);
+		if (viewDescriptorCollection) {
+			this._register(viewDescriptorCollection.onDidChangeActiveViews(() => this.onDidChangeViewDescriptors(viewDescriptorCollection.activeViewDescriptors)));
+			this.onDidChangeViewDescriptors(viewDescriptorCollection.activeViewDescriptors);
+		}
 	}
 
 	isVisible(id: string): boolean {
diff --git a/src/vs/workbench/common/views.ts b/src/vs/workbench/common/views.ts
index 15fa9d4b93e638f4e2a7df60a2d270327110e855..f5effa730ab7731a7adef8f4ed3e4fb04ce6b51b 100644
--- a/src/vs/workbench/common/views.ts
+++ b/src/vs/workbench/common/views.ts
@@ -289,7 +289,7 @@ export interface IViewsService {
 
 	openView(id: string, focus?: boolean): Promise<IView | null>;
 
-	getViewDescriptors(container: ViewContainer): IViewDescriptorCollection;
+	getViewDescriptors(container: ViewContainer): IViewDescriptorCollection | null;
 }
 
 // Custom views