stride3d/stride · error · ArgumentException

The given source panel does not match the currently set…

Error message

The given source panel does not match the currently set root element

What it means

Thrown by UIPageRootViewModel.ReplaceRootElement when the given sourcePanel's Id does not match the single root element of the UIPage asset. A UIPage has exactly one root, and this method replaces that root, so it validates that the panel being removed is in fact the current root.

Solutions

1. Pass the panel corresponding to Asset.Asset.Hierarchy.RootParts.Single() as sourcePanel.
2. Verify sourcePanel.Id.ObjectId equals RootParts.Single().Id before calling.
3. Re-resolve the root PanelViewModel from the current asset state instead of caching it.

Example fix

// before
pageRoot.ReplaceRootElement(somePanel, newHierarchy, targetPanelId);
// after
var rootId = pageRoot.Asset.Asset.Hierarchy.RootParts.Single().Id;
if (somePanel.Id.ObjectId != rootId) throw new ArgumentException("Not the current root");
pageRoot.ReplaceRootElement(somePanel, newHierarchy, targetPanelId);

bool isCurrentRoot = sourcePanel.Id.ObjectId == pageRoot.Asset.Asset.Hierarchy.RootParts.Single().Id;

static bool IsCurrentRoot(UIPageRootViewModel root, PanelViewModel p) => p.Id.ObjectId == root.Asset.Asset.Hierarchy.RootParts.Single().Id;

try { pageRoot.ReplaceRootElement(panel, hierarchy, targetId); } catch (ArgumentException ex) { /* pass the actual root panel */ }

When it happens

Trigger: Calling ReplaceRootElement with any panel other than the page's single root (e.g. a nested panel, or a panel from another asset/page) so sourcePanel.Id.ObjectId != RootParts.Single().Id.

Common situations: Reusing library-replacement logic on a UIPage with a non-root panel; stale panel references after the root was already replaced once; drag/drop handlers targeting inner panels.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• The given source panel is not a root element of this asset.
• Can't change the name of a UIPage object.
• A UIPage asset can't have more than one root.
• Custom strides is not supported with packed PixelFormats
• Unable to find the base

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/22f26e3cf17d6f97. Report an issue: GitHub.

Appendix: source

Thrown at sources/editor/Stride.Assets.Presentation/AssetEditors/UIPageEditor/ViewModels/UIPageRootViewModel.cs:43

        public UIPageRootViewModel([NotNull] UIEditorBaseViewModel editor, [NotNull] UIPageViewModel asset, UIElementDesign rootElement)
            : base(editor, asset, rootElement?.Yield())
        {
            NotifyGameSidePartAdded().Forget();
        }

        /// <inheritdoc />
        [NotNull]
        public override string Name { get => "UI Page"; set => throw new NotSupportedException("Can't change the name of a UIPage object."); }

        [CanBeNull]
        public UIElementViewModel RootElement => RootElements.SingleOrDefault();

        /// <inheritdoc />
        public override void ReplaceRootElement(PanelViewModel sourcePanel, AssetCompositeHierarchyData<UIElementDesign, UIElement> hierarchy, Guid targetPanelId)
        {
            if (sourcePanel == null) throw new ArgumentNullException(nameof(sourcePanel));
            if (sourcePanel.Id.ObjectId != Asset.Asset.Hierarchy.RootParts.Single().Id)
                throw new ArgumentException(@"The given source panel does not match the currently set root element", nameof(sourcePanel));

            Asset.AssetHierarchyPropertyGraph.RemovePartFromAsset(sourcePanel.UIElementDesign);
            Asset.AssetHierarchyPropertyGraph.AddPartToAsset(hierarchy.Parts, hierarchy.Parts[targetPanelId], null, Asset.Asset.Hierarchy.RootParts.Count);
        }

        /// <inheritdoc />
        // ReSharper disable once RedundantAssignment
        protected override bool CanAddOrInsertChildren(IReadOnlyCollection<object> children, ref string message)
        {
            if (RootElement != null)
                return ((IAddChildViewModel)RootElement).CanAddChildren(children, AddChildModifiers.None, out message);

            var count = children.Count;
            if (count == 0)
            {
                message = "Empty selection";
                return false;
            }

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