Using WinUI 2.6.1 in a .net core 3.1 app (XAML island) crashes at startup on older Windows version

Describe the bug

The application based on .net core 3.1 crashes during launch on Windows version 1903 when using WinUI 2.6.1 while version 2.6.0 works fine (just replacing the winui dll in the output directory is sufficient to make it work). The bug does not occur on the latest Windows version (21H1). Attached is the stack trace from windbg:

Access violation - code c0000005

[0x0]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::Windows::Foundation::IUnknown::unconditional_release_ref + 0x10   
[0x1]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::Windows::Foundation::IUnknown::release_ref + 0xf   
[0x2]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::Windows::Foundation::IUnknown::{dtor} + 0xf   
[0x3]   Microsoft_UI_Xaml_7ffbfc0d0000!XamlControlsResources::UpdateAcrylicBrushesDarkTheme + 0xea   
[0x4]   Microsoft_UI_Xaml_7ffbfc0d0000!XamlControlsResources::UpdateSource + 0x1ba   
[0x5]   Microsoft_UI_Xaml_7ffbfc0d0000!XamlControlsResources::{ctor} + 0x38   
[0x6]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::impl::heap_implements<XamlControlsResources>::heap_implements<XamlControlsResources> + 0x45   
[0x7]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::make + 0x26   
[0x8]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::Microsoft::UI::Xaml::Controls::factory_implementation::XamlControlsResourcesT<winrt::Microsoft::UI::Xaml::Controls::XamlControlsResourcesFactory,XamlControlsResources>::ActivateInstance + 0x26   
[0x9]   Microsoft_UI_Xaml_7ffbfc0d0000!winrt::impl::produce<winrt::Microsoft::UI::Xaml::Controls::XamlControlsResourcesFactory,winrt::Windows::Foundation::IActivationFactory>::ActivateInstance + 0x42   
[0xa]   0x7ffba5aaa14c   
[0xb]   0x7ffba5aa915e   
[0xc]   0x7ffba37d95e7   
[0xd]   System_Windows_Forms!System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry)$##60012A5 + 0xf0   
[0xe]   System_Windows_Forms!System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(System.Object)$##60012A4 + 0x3c   
[0xf]   System_Private_CoreLib!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)$##6001E8E + 0x76   
[0x10]   System_Private_CoreLib!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)$##6001E8D + 0x10   
[0x11]   System_Windows_Forms!System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry)$##60012A3 + 0x80   
[0x12]   System_Windows_Forms!System.Windows.Forms.Control.InvokeMarshaledCallbacks()$##60012A6 + 0xf7   
[0x13]   System_Windows_Forms!System.Windows.Forms.Control.WndProc(System.Windows.Forms.Message ByRef)$##60013CC + 0xa03   
[0x14]   System_Windows_Forms!System.Windows.Forms.Control+ControlNativeWindow.OnMessage(System.Windows.Forms.Message ByRef)$##6005621 + 0x1f   
[0x15]   System_Windows_Forms!System.Windows.Forms.Control+ControlNativeWindow.WndProc(System.Windows.Forms.Message ByRef)$##6005624 + 0x102   
[0x16]   System_Windows_Forms!System.Windows.Forms.NativeWindow.Callback(IntPtr, Int32, IntPtr, IntPtr)$##6002E1C + 0xa1   
[0x17]   0x7ffba34252e0   
[0x18]   coreclr!coreclr_shutdown_2 + 0xbc5b   
[0x19]   USER32!UserCallWinProcCheckWow + 0x2bd   
[0x1a]   USER32!DispatchMessageWorker + 0x1e2   
[0x1b]   0x7ffba37d5337   
[0x1c]   System_Windows_Forms!System.Windows.Forms.Application+ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr, Int32, Int32)$##600537C + 0x391   
[0x1d]   System_Windows_Forms!System.Windows.Forms.Application+ThreadContext.RunMessageLoopInner(Int32, System.Windows.Forms.ApplicationContext)$##60053AA + 0x416   
[0x1e]   System_Windows_Forms!System.Windows.Forms.Application+ThreadContext.RunMessageLoop(Int32, System.Windows.Forms.ApplicationContext)$##60053A9 + 0x46   
[0x1f]   System_Windows_Forms!System.Windows.Forms.Application.Run(System.Windows.Forms.Form)$##6000AEC + 0x3b   
[0x20]   0x7ffba341630e   
[0x21]   coreclr!coreclr_shutdown_2 + 0xbb43   
[0x22]   coreclr!coreclr_initialize + 0xda772   
[0x23]   coreclr!coreclr_initialize + 0xe1739   
[0x24]   coreclr!coreclr_initialize + 0xe1bc7   
[0x25]   coreclr!coreclr_initialize + 0xe2371   
[0x26]   coreclr!coreclr_execute_assembly + 0x101   
[0x27]   hostpolicy!coreclr_t::execute_assembly + 0x2d   
[0x28]   hostpolicy!run_app_for_context + 0x387   
[0x29]   hostpolicy!run_app + 0x46   
[0x2a]   hostpolicy!corehost_main + 0x132   
[0x2b]   hostfxr!execute_app + 0x2e3   
[0x2c]   hostfxr!`anonymous namespace'::read_config_and_execute + 0xa8   
[0x2d]   hostfxr!fx_muxer_t::handle_exec_host_command + 0x15d   
[0x2e]   hostfxr!fx_muxer_t::execute + 0x1fc   
[0x2f]   hostfxr!hostfxr_main_startupinfo + 0x9c   
[0x30]   apphost!exe_start + 0x651   
[0x31]   apphost!wmain + 0x88   
[0x32]   apphost!invoke_main + 0x22   
[0x33]   apphost!__scrt_common_main_seh + 0x10c   
[0x34]   KERNEL32!BaseThreadInitThunk + 0x14   
[0x35]   ntdll!RtlUserThreadStart + 0x21   

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Go to ‘…’
2. Click on ‘…’

Expected behavior

The application should launch properly

Screenshots

Version Info

NuGet package version:

[Microsoft.UI.Xaml 2.6.1]

Windows app type:

UWP	Win32
	Yes

Windows 10 version	Saw the problem?
21H1 (19043)	No
October 2020 Update (19042)
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)	Yes
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context

[jaimecbernardo]

I can confirm the latest release “2.7.0-prerelease.210913003” fixes this issue for me.

[jaimecbernardo]

@asklar , I had opened the duplicate issue https://github.com/microsoft/microsoft-ui-xaml/issues/5546 .

I’ve tested 2.6.2-prerelease.210818003. The issue is still present. I’ve tested 2.7.0-prerelease.210816001. The issue is still present.