stride3d/stride · error · ArgumentException

GameWindow should have either a SwapChainPanel or a…

Error message

GameWindow should have either a SwapChainPanel or a CoreWindow

What it means

GameWindowUWP.ClientBounds requires either a SwapChainPanel or a CoreWindow to measure the window rectangle; when neither is present it throws an ArgumentException naming the missing components. On UWP the render target is hosted by one of these two XAML/Core objects, so a GameWindow without either has no defined client bounds.

Solutions

1. Ensure the SwapChainPanel is assigned to the GameWindow before reading ClientBounds (wait for the XAML panel to load).
2. Defer bounds queries until after CoreWindow activation (WindowActivated/Loaded callbacks) rather than during construction.
3. Fix the hosting code so exactly one of SwapChainPanel/CoreWindow is provided when creating GameWindowUWP.

Example fix

// before
var bounds = gameWindow.ClientBounds; // panel not yet assigned
// after
swapChainPanel.Loaded += (s, e) =>
{
    gameWindow.SwapChainPanel = swapChainPanel;
    var bounds = gameWindow.ClientBounds;
};

bool CanReadBounds(GameWindowUWP w) => w.SwapChainPanel != null || w.CoreWindow != null;
var bounds = CanReadBounds(gameWindow) ? gameWindow.ClientBounds : Rect.Empty;

bool HasHostSurface(GameWindowUWP w) => w.SwapChainPanel != null || w.CoreWindow != null;

try { var b = gameWindow.ClientBounds; }
catch (ArgumentException ex) when (ex.Message.Contains("SwapChainPanel"))
{
    // wait for panel binding / CoreWindow activation, then retry
}

When it happens

Trigger: Accessing ClientBounds on a GameWindowUWP whose SwapChainPanel and CoreWindow are both null — e.g. the window was constructed but not yet bound to the XAML SwapChainPanel or activated CoreWindow, or queried during/after app suspension.

Common situations: Reading ClientBounds too early during UWP startup before panel binding, custom UWP hosting that never sets SwapChainPanel, or accessing bounds after CoreWindow activation was lost.

Understand the failure class

Background: "not installed", "pip install", "required for": how missing-dependency errors surface across open-source libraries — this error's family across 34 libraries.

Related errors

• The path [ ] contains access to a member of a null object.
• Unable to retrieve the value of this member path on this…
• url cannot be null or empty.
• ArgumentNullException
• Array is null

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/ecdb425d256eb3b2. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Games/WindowsStore/GameWindowUWP.cs:99

        public override Rectangle ClientBounds
        {
            get
            {
                if (swapChainPanel != null)
                {
                    return new Rectangle(0, 0, 
                        (int)(swapChainPanel.ActualWidth  * swapChainPanel.CompositionScaleX + 0.5f),
                        (int)(swapChainPanel.ActualHeight * swapChainPanel.CompositionScaleY + 0.5f));

                }

                if (coreWindow != null)
                {
                    return new Rectangle((int)(coreWindow.Bounds.X), (int)(coreWindow.Bounds.Y), (int)(coreWindow.Bounds.Width), (int)(coreWindow.Bounds.Height));
                }

                throw new ArgumentException($"{nameof(GameWindow)} should have either a {nameof(SwapChainPanel)} or a {nameof(CoreWindow)}");
            }
        }

        public override DisplayOrientation CurrentOrientation => DisplayOrientation.Default;

        public override bool IsMinimized => false;
        
        public override bool Focused => focused;

        private bool isMouseVisible;
        private CoreCursor cursor;

        public override bool IsMouseVisible
        {
            get
            {
                return isMouseVisible;
            }

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