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Reproduction steps:
1. Create a new project
2. Create MultiColumnListView Standard Element (GameObject > UI Toolkit > Standard Elements > UI Library…)
3. Create UI Document
4. Right-click on the Multi Column List View and create any Standard Element
5. Observe the error messages in the Console
Actual result: “InvalidOperationException: You can't add directly to this VisualElement. Use hierarchy.Add() if you know what you're doing.” error is thrown
Expected result: Error message that states the problem, the cause and the solution in neutral language is thrown
Reproducible with: 6000.6.0a7, 6000.6.0b5, 6000.7.0a3
Couldn’t reproduce with: 6000.0.80f1, 6000.3.20f1, 6000.5.5f1, 6000.6.0a6 (No Standard Elements option)
Reproduced on: Windows 11, macOS Tahoe 26.5 (M4)
Note: Full error:
InvalidOperationException: You can't add directly to this VisualElement. Use hierarchy.Add() if you know what you're doing. UnityEngine.UIElements.VisualElement.Add (UnityEngine.UIElements.VisualElement child) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/VisualElementHierarchy.cs:213) UnityEngine.UIElements.VisualTreeAsset.CloneSetupRecursively (UnityEngine.UIElements.VisualElementAsset asset, UnityEngine.UIElements.CreationContext context, UnityEngine.UIElements.VisualElementAssetReferenceTable+DocumentNode parentAuthoringNode) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UXML/VisualTreeAsset.cs:726) UnityEngine.UIElements.VisualTreeAsset.CloneTree (UnityEngine.UIElements.VisualElement target, UnityEngine.UIElements.CreationContext cc, UnityEngine.UIElements.VisualElementAssetReferenceTable+DocumentNode parentAuthoringNode) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UXML/VisualTreeAsset.cs:605) UnityEngine.UIElements.VisualTreeAsset.CloneTree (UnityEngine.UIElements.VisualElement target, System.Int32& firstElementIndex, System.Int32& elementAddedCount) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UXML/VisualTreeAsset.cs:546) UnityEngine.UIElements.VisualTreeAsset.CloneTree (UnityEngine.UIElements.VisualElement target) (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/UXML/VisualTreeAsset.cs:523) Unity.UIToolkit.Editor.VisualElementEditingStage.CloneTree () (at /Users/bokken/build/output/unity/unity/Modules/UIToolkitAuthoringEditor/Managed/Stages/VisualElementEditingStage.cs:148) Unity.UIToolkit.Editor.VisualElementEditingStage.RequestRefresh () (at /Users/bokken/build/output/unity/unity/Modules/UIToolkitAuthoringEditor/Managed/Stages/VisualElementEditingStage.cs:99) Unity.UIToolkit.Editor.MenuUtility.ExecuteAdd (Unity.UIToolkit.Editor.VisualElementEditingStage stage, Unity.UIToolkit.Editor.MenuUtility+AddRequest request, UnityEngine.UIElements.VisualElementAsset parentVea) (at /Users/bokken/build/output/unity/unity/Modules/UIToolkitAuthoringEditor/Managed/Menu/MenuUtility.cs:351) Unity.UIToolkit.Editor.MenuUtility.AddElement (Unity.UIToolkit.Editor.MenuUtility+AddRequest request, System.Boolean addAsSibling, System.Boolean parentNewGameObjectUnderSelection) (at /Users/bokken/build/output/unity/unity/Modules/UIToolkitAuthoringEditor/Managed/Menu/MenuUtility.cs:58) Unity.UIToolkit.Editor.MenuUtility.AddElementAsLastChild (System.Type elementType, System.String variantName) (at /Users/bokken/build/output/unity/unity/Modules/UIToolkitAuthoringEditor/Managed/Menu/MenuUtility.cs:39) Unity.UIToolkit.Editor.StageContextMenuUtility+<>c__DisplayClass20_0.<PopulateElementOperations>b__1 (UnityEngine.UIElements.DropdownMenuAction _) (at /Users/bokken/build/output/unity/unity/Modules/UIToolkitAuthoringEditor/Managed/Stages/StageContextMenuUtility.cs:240) UnityEngine.UIElements.DropdownMenuAction.Execute () (at /Users/bokken/build/output/unity/unity/Modules/UIElements/Core/DropdownMenu.cs:224) UnityEditor.UIElements.EditorMenuExtensions+<>c__DisplayClass0_0.<PrepareMenu>b__0 () (at /Users/bokken/build/output/unity/unity/Editor/Mono/UIElements/EditorMenuExtensions.cs:36) UnityEditor.GenericMenu.CatchMenu (System.Object userData, System.String[] options, System.Int32 selected) (at /Users/bokken/build/output/unity/unity/Editor/Mono/GUI/GenericMenu.cs:164) UnityEngine.StackTraceUtility:ExtractStringFromExceptionInternal(Object, String&, String&) (at /Users/bokken/build/output/unity/unity/Runtime/Export/Scripting/StackTrace.cs:50)
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