fix #59752

src/vs/workbench/browser/parts/editor/editorPart.ts

@@ -865,6 +865,7 @@ export class EditorPart extends Part implements EditorGroupsServiceImpl, IEditor
 		}
 
 		// Create new
+		const groupViews: IEditorGroupView[] = [];
 		const gridWidget = SerializableGrid.deserialize(serializedGrid, {
 			fromJSON: (serializedEditorGroup: ISerializedEditorGroup) => {
 				let groupView: IEditorGroupView;
@@ -874,6 +875,8 @@ export class EditorPart extends Part implements EditorGroupsServiceImpl, IEditor
 					groupView = this.doCreateGroupView(serializedEditorGroup);
 				}
 
+				groupViews.push(groupView);
+
 				if (groupView.id === activeGroupId) {
 					this.doSetGroupActive(groupView);
 				}
@@ -882,6 +885,18 @@ export class EditorPart extends Part implements EditorGroupsServiceImpl, IEditor
 			}
 		}, { styles: { separatorBorder: this.gridSeparatorBorder } });
 
+		// If the active group was not found when restoring the grid
+		// make sure to make at least one group active. We always need
+		// an active group.
+		if (!this._activeGroup) {
+			this.doSetGroupActive(groupViews[0]);
+		}
+
+		// Validate MRU group views matches grid widget state
+		if (this.mostRecentActiveGroups.some(groupId => !this.getGroup(groupId))) {
+			this.mostRecentActiveGroups = groupViews.map(group => group.id);
+		}
+
 		// Set it
 		this.doSetGridWidget(gridWidget);
 	}