diff --git a/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts b/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts
index dda0ddfc609ed94404286aa65cbd0d811690da58..38363d5d2d23f91023d1393e3a4293af4afb576e 100644
--- a/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts
+++ b/src/vs/workbench/contrib/notebook/browser/notebook.contribution.ts
@@ -197,6 +197,7 @@ export class NotebookContribution extends Disposable implements IWorkbenchContri
 			const visibleNotebookEditors = editorService.visibleEditorPanes
 				.filter(pane => (pane as any).isNotebookEditor)
 				.map(pane => pane.getControl() as INotebookEditor)
+				.filter(control => !!control)
 				.map(editor => editor.getId());
 
 			this.notebookService.updateVisibleNotebookEditor(visibleNotebookEditors);