unoplatform/uno · critical · InvalidOperationException

wglCreateContext failed

Error message

wglCreateContext failed

What it means

After the pixel format is set, wglCreateContext(_hdc) creates the GL rendering context; it returns NULL on failure and the wrapper throws InvalidOperationException. wglCreateContext fails when the HDC has no valid pixel format set, the driver cannot allocate a context (out of GPU memory), the GDI/DLL opengl32 is unavailable, or the application is in a session type (e.g. certain service/RDP contexts) that disallows GL context creation.

Source

Thrown at src/AddIns/Uno.WinUI.Graphics3DGL/Windows/WinUINativeOpenGLWrapper.cs:75

		// To inspect the chosen pixel format:
		// WindowsRenderingNativeMethods.PIXELFORMATDESCRIPTOR temp_pfd = default;
		// WindowsRenderingNativeMethods.DescribePixelFormat(_hdc, _pixelFormat, (uint)Marshal.SizeOf<WindowsRenderingNativeMethods.PIXELFORMATDESCRIPTOR>(), ref temp_pfd);

		if (pixelFormat == 0)
		{
			throw new InvalidOperationException("ChoosePixelFormat failed");
		}

		if (WindowsRenderingNativeMethods.SetPixelFormat(_hdc, pixelFormat, ref pfd) == 0)
		{
			throw new InvalidOperationException("SetPixelFormat failed");
		}

		_glContext = WindowsRenderingNativeMethods.wglCreateContext(_hdc);

		if (_glContext == IntPtr.Zero)
		{
			throw new InvalidOperationException("wglCreateContext failed");
		}
	}

	// https://sharovarskyi.com/blog/posts/csharp-win32-opengl-silknet/
	public bool TryGetProcAddress(string proc, out nint addr)
	{
		if (_opengl32.Value != IntPtr.Zero && NativeLibrary.TryGetExport(_opengl32.Value, proc, out addr))
		{
			return true;
		}

		addr = WindowsRenderingNativeMethods.wglGetProcAddress(proc);
		return addr != IntPtr.Zero;
	}

	public nint GetProcAddress(string proc)
	{
		if (TryGetProcAddress(proc, out var address))

View on GitHub (pinned to 0418340488)

Solutions

1. Guarantee ChoosePixelFormat + SetPixelFormat succeeded on the same HDC before wglCreateContext (chain the checks).
2. Reduce the number of simultaneously live GL contexts to free GPU handles.
3. Install/repair GPU drivers and opengl32.dll; verify the session is an interactive desktop.
4. Call Marshal.GetLastWin32Error / GetLastError for the specific failure reason and surface it.

if (_glContext == IntPtr.Zero)
{
	int err = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
	throw new InvalidOperationException($"wglCreateContext failed (Win32 {err})");
}

When it happens

Trigger: HDC's pixel format not actually set (so [53] should have thrown earlier but didn't, e.g. custom code path); GPU memory exhausted; opengl32.dll missing/unloaded; session has no interactive desktop.

Common situations: Too many live GL contexts exhausting GPU handles; corrupt/missing GPU driver; running the GL host in a non-interactive session; running on a server with no GPU and a software GL stack that rejects context creation.

Related errors

• No function was found with the name {proc}.
• ChoosePixelFormat failed
• SetPixelFormat failed
• 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/0dd7b66e0d6ccef0. Report an issue: GitHub.