unoplatform/uno · error · PlatformNotSupportedException

This platform does not support SKCanvasElement. For more inf

Error message

This platform does not support SKCanvasElement. For more information: https://aka.platform.uno/skcanvaselement

What it means

SKCanvasElement's protected constructor throws PlatformNotSupportedException when IsSupportedOnCurrentPlatform() is false. On non-CROSSRUNTIME builds IsSupportedOnCurrentPlatform() is a hardcoded `false`; on CROSSRUNTIME builds it returns ApiExtensibility.IsRegistered<SKCanvasVisualBaseFactory>(). So the throw means either the type is being constructed on a TFM that compiles it without CROSSRUNTIME, or no SKCanvasVisualBaseFactory is registered. This fires earlier and more cheaply than [47].

Source

Thrown at src/AddIns/Uno.WinUI.Graphics2DSK/SKCanvasElement.cs:42

	{
		if (ApiExtensibility.CreateInstance<SKCanvasVisualBaseFactory>(this, out var factory))
		{
			return _skCanvasVisual = factory.CreateInstance((o, size) => RenderOverride((SKCanvas)o, size), Compositor.GetSharedCompositor());
		}
		else
		{
			throw new InvalidOperationException($"Failed to create an instance of {nameof(SKCanvasVisualBase)}");
		}
	}

	internal override bool IsViewHit() => true;
#endif

	protected SKCanvasElement()
	{
		if (!IsSupportedOnCurrentPlatform())
		{
			throw new PlatformNotSupportedException($"This platform does not support {nameof(SKCanvasElement)}. For more information: https://aka.platform.uno/skcanvaselement");
		}
	}

#if CROSSRUNTIME
	public static bool IsSupportedOnCurrentPlatform() => ApiExtensibility.IsRegistered<SKCanvasVisualBaseFactory>();
#else
	public static bool IsSupportedOnCurrentPlatform() => false;
#endif

	/// <summary>
	/// Invalidates the element and triggers a redraw.
	/// </summary>
#if CROSSRUNTIME
	public void Invalidate() => _skCanvasVisual?.Invalidate();
#else
#pragma warning disable CS0109 // Member does not hide an inherited member; new keyword is not required
	public new void Invalidate() { }
#pragma warning restore CS0109 // Member does not hide an inherited member; new keyword is not required

View on GitHub (pinned to 0418340488)

Solutions

1. Call SKCanvasElement.IsSupportedOnCurrentPlatform() before constructing the element and avoid instantiation when it returns false.
2. Target a Skia-supported head (Skia Desktop / Skia-mobile) and ensure the SKCanvasVisualBaseFactory-registering host package is referenced.
3. If the type was compiled without CROSSRUNTIME, switch to the CROSSRUNTIME configuration or use a different drawing surface.

Example fix

// before
var el = new SKCanvasElement();

// after
if (!SKCanvasElement.IsSupportedOnCurrentPlatform())
{
	throw new PlatformNotSupportedException("SKCanvasElement not available on this head; use a Skia target.");
}
var el = new SKCanvasElement();

if (!SKCanvasElement.IsSupportedOnCurrentPlatform())
{
	throw new PlatformNotSupportedException("SKCanvasElement unavailable on this head.");
}
var el = new SKCanvasElement();

static bool CanUseSKCanvasElement() => SKCanvasElement.IsSupportedOnCurrentPlatform();

When it happens

Trigger: Constructing SKCanvasElement on a target where the Graphics2DSK add-in was compiled without CROSSRUNTIME defined, or where no SKCanvasVisualBaseFactory is registered for the runtime.

Common situations: Using SKCanvasElement in a head that does not support Skia 2D canvases (e.g. WASM-DOM, native iOS/Android without Skia); referencing the add-in but omitting the Skia host package that registers the factory.

Related errors

• Failed to create an instance of SKCanvasVisualBase
• Vertex shader failed to compile: {infoLog}
• Fragment shader failed to compile: {infoLog}
• PInvoke.RegisterClassEx failed: {Win32Helper.GetErrorMessage
• PInvoke.CreateWindowEx failed: {Win32Helper.GetErrorMessage(

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/3ce1afb399271497. Report an issue: GitHub.