Templated XAML controls for WinUI 3 apps with C# won't work and crash.

[blueblizza]

Describe the bug
Templated XAML controls for WinUI 3 apps with C# won't work and crash.

Steps to reproduce the bug
1.Create a "Blank App, Packaged (WinUI in Desktop) project template" in WinUI3
Follow the instructions as "Templated XAML controls for WinUI 3 apps with C#"
https://docs.microsoft.com/en-us/windows/apps/winui/winui3/xaml-templated-controls-csharp-winui-3

2.Press F5(Starting Debugging)

3.get error output and crashed
mincore\com\oleaut32\dispatch\ups.cpp(2122)\OLEAUT32.dll!76B4245F: (caller: 76B43D7F) ReturnHr(1) tid(57f8) 8002801D Library not registered.
D:\a\1\s\dev\MRTCore\mrt\Core\src\MRM.cpp(276)\MRM.dll!7A4DDEA1: (caller: 7A4DF6A8) ReturnHr(1) tid(57f8) 80073B17 NamedResource Not Found.
D:\a\1\s\dev\MRTCore\mrt\Core\src\MRM.cpp(403)\MRM.dll!7A4DF6C5: (caller: 7A48BF9E) ReturnHr(2) tid(57f8) 80073B17 NamedResource Not Found.
D:\a\1\s\dev\MRTCore\mrt\Core\src\MRM.cpp(755)\MRM.dll!7A4DF8E0: (caller: 7A48BF9E) ReturnHr(3) tid(57f8) 80073B17 NamedResource Not Found.
Exception thrown at 0x7761A892 (KernelBase.dll) in TemplatedXAMLDemo.exe: WinRT originate error - 0x80073B17 : 'NamedResource Not Found.'.
Exception thrown at 0x7761A892 in TemplatedXAMLDemo.exe: Microsoft C++ exception: winrt::hresult_error at memory location 0x02D7DE88.

Expected behavior
Build and run the app and you will see the templated control, with the background color and label specified.

Version Info

NuGet package version:
[Microsoft.VCRTForwarders.140 1.0.7]
[Microsoft.WinUI 3.0.0-preview3.201113.0]

Windows app type:
C# WinUI
Blank App, Packaged (WinUI in Desktop) project

Windows 10 version	Saw the problem?
20H2 Build (19042.685)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
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
my source repo: https://github.com/blueblizza/TemplatedXAMLDemo

[stevenbrix]

@blueblizza, does disabling mixed mode debugging fix this issue?

[blueblizza]

@blueblizza, does disabling mixed mode debugging fix this issue?

hi @stevenbrix , I change debugger type to "managed only" and this issue is fixed.
On the other hand, if I change debugger type to "native only", this issue reproduced.

[stevenbrix]

Thanks @blueblizza for confirming. Do you need mixed mode or native only debugging? Our plan to address this is to change the default to managed debugging only

[blueblizza]

Hi, @stevenbrix, I need mixed mode, because I also include a WinRT algorithm module in my project written in C++.

[stevenbrix]

Gotcha 👍

Until the next release is out where we have this fixed, you can disable the exception in the exception settings:

[blueblizza]

Thanks, @stevenbrix
This solution works well.

[stevenbrix]

This is a dupe of #3868