diff --git a/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts b/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts
index aa74492c55a..ceaeec219d8 100644
--- a/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts
+++ b/extensions/vscode-api-tests/src/singlefolder-tests/notebook.document.test.ts
@@ -351,7 +351,6 @@ suite('Notebook Document', function () {
 
 
 	test('#117273, Add multiple outputs', async function () {
-		this.skip();
 
 		const resource = await utils.createRandomFile(undefined, undefined, '.nbdtest');
 		const document = await vscode.notebook.openNotebookDocument(resource);
@@ -372,26 +371,13 @@ suite('Notebook Document', function () {
 		assert.deepStrictEqual(document.cells[0].outputs[0].outputs[0].metadata, { outputType: 'stream', streamName: 'stdout' });
 
 		const edit2 = new vscode.WorkspaceEdit();
-		// All of the following edit operations fail.
 		edit2.appendNotebookCellOutput(document.uri, 0, [
 			new vscode.NotebookCellOutput(
 				[new vscode.NotebookCellOutputItem('hello', '1', { outputType: 'stream', streamName: 'stderr' })],
 				{ outputType: 'stream', streamName: 'stderr' }
 			)
 		]);
-		// edit2.replaceNotebookCellOutput(document.uri, 0, [
-		// 	...document.cells[0].outputs,
-		// 	new vscode.NotebookCellOutput([new vscode.NotebookCellOutputItem('hello', '1', { outputType: 'stream', streamName: 'stderr' })], { outputType: 'stream', streamName: 'stderr' })
-		// ]);
-		// edit2.replaceNotebookCellOutput(document.uri, 0, [
-		// 	...document.cells[0].outputs,
-		// 	new vscode.NotebookCellOutput([new vscode.NotebookCellOutputItem('application/x.notebook.stream', '1', { outputType: 'stream', streamName: 'stderr' })], { outputType: 'stream', streamName: 'stderr' })
-		// ]);
-		// This wasn't working, i had to revert to using `replaceNotebookCellOutput` (could be because we had two output in the cell).
-		// edit2.appendNotebookCellOutputItems(document.uri, 0, document.cells[0].outputs[1].id, [
-		// 	new vscode.NotebookCellOutputItem('hello', 'Append to existing stderr when we have two outputs (one for stdout & one for stderr)', { outputType: 'stream', streamName: 'stderr' })
-		// ]);
-		success = await vscode.workspace.applyEdit(edit);
+		success = await vscode.workspace.applyEdit(edit2);
 		assert.ok(success);
 
 		assert.strictEqual(document.cells[0].outputs.length, 2);
diff --git a/src/vs/workbench/contrib/notebook/test/notebookTextModel.test.ts b/src/vs/workbench/contrib/notebook/test/notebookTextModel.test.ts
index df4d6a86b6c..6caa4fd6624 100644
--- a/src/vs/workbench/contrib/notebook/test/notebookTextModel.test.ts
+++ b/src/vs/workbench/contrib/notebook/test/notebookTextModel.test.ts
@@ -351,4 +351,41 @@ suite('NotebookTextModel', () => {
 			}
 		);
 	});
+
+
+	test('Updating appending/updating output in Notebooks does not work as expected #117273', function () {
+		withTestNotebook(instantiationService, blukEditService, undoRedoService, [
+			['var a = 1;', 'javascript', CellKind.Code, [], { editable: true }]
+		], (_editor, _view, model) => {
+
+			assert.strictEqual(model.cells.length, 1);
+			assert.strictEqual(model.cells[0].outputs.length, 0);
+
+			const success1 = model.applyEdits(
+				model.versionId,
+				[{
+					editType: CellEditType.Output, index: 0, outputs: [
+						{ outputId: 'out1', outputs: [{ mime: 'application/x.notebook.stream', value: 1 }] }
+					],
+					append: false
+				}], true, undefined, () => undefined, undefined, false
+			);
+
+			assert.ok(success1);
+			assert.strictEqual(model.cells[0].outputs.length, 1);
+
+			const success2 = model.applyEdits(
+				model.versionId,
+				[{
+					editType: CellEditType.Output, index: 0, outputs: [
+						{ outputId: 'out2', outputs: [{ mime: 'application/x.notebook.stream', value: 1 }] }
+					],
+					append: true
+				}], true, undefined, () => undefined, undefined, false
+			);
+
+			assert.ok(success2);
+			assert.strictEqual(model.cells[0].outputs.length, 2);
+		});
+	});
 });