diff --git a/src/vs/workbench/contrib/chat/browser/chatEditing/chatEditingModifiedNotebookEntry.ts b/src/vs/workbench/contrib/chat/browser/chatEditing/chatEditingModifiedNotebookEntry.ts
index 145cb1a8d24..d63450e6504 100644
--- a/src/vs/workbench/contrib/chat/browser/chatEditing/chatEditingModifiedNotebookEntry.ts
+++ b/src/vs/workbench/contrib/chat/browser/chatEditing/chatEditingModifiedNotebookEntry.ts
@@ -112,7 +112,7 @@ export class ChatEditingModifiedNotebookEntry extends AbstractChatEditingModifie
 			const loggingService = accessor.get(INotebookLoggingService);
 			const resourceRef: IReference<IResolvedNotebookEditorModel> = await resolver.resolve(uri);
 			const notebook = resourceRef.object.notebook;
-			const originalUri = ChatEditingNotebookFileSystemProvider.getSnapshotFileURI(telemetryInfo.requestId, notebook.uri.path);
+			const originalUri = ChatEditingNotebookFileSystemProvider.getSnapshotFileURI(telemetryInfo.requestId, notebook.uri.scheme === Schemas.untitled ? `/${notebook.uri.path}` : notebook.uri.path);
 			const [options, buffer] = await Promise.all([
 				notebookService.withNotebookDataProvider(resourceRef.object.notebook.notebookType),
 				notebookService.createNotebookTextDocumentSnapshot(notebook.uri, SnapshotContext.Backup, CancellationToken.None).then(s => streamToBuffer(s))
diff --git a/src/vs/workbench/contrib/notebook/browser/services/notebookServiceImpl.ts b/src/vs/workbench/contrib/notebook/browser/services/notebookServiceImpl.ts
index b1670958f9f..1bc15e00ae3 100644
--- a/src/vs/workbench/contrib/notebook/browser/services/notebookServiceImpl.ts
+++ b/src/vs/workbench/contrib/notebook/browser/services/notebookServiceImpl.ts
@@ -871,6 +871,11 @@ export class NotebookService extends Disposable implements INotebookService {
 	}
 
 	hasSupportedNotebooks(resource: URI): boolean {
+		if (this._models.has(resource)) {
+			// it might be untitled
+			return true;
+		}
+
 		const contribution = this.notebookProviderInfoStore.getContributedNotebook(resource);
 		if (!contribution.length) {
 			return false;