What would cause WinRT.ActivationFactory to be null long after Desktop WinUI3 app has been running?

[sharpninja]

An error is occurring when instantiating a TextBox. Placing a breakpoint in ThrowExceptionForHR allows me to capture the below stack. Also, when setting the context to this frame

Microsoft.WinUI.dll!WinRT.WinrtModule.GetActivationFactory(string runtimeClassId = "Microsoft.UI.Xaml.Application")

I can see in the locals window these variables:

	Name	Value	Type
◢	this	{WinRT.ActivationFactory<Microsoft.UI.Xaml.Application>}	WinRT.BaseActivationFactory {WinRT.ActivationFactory<Microsoft.UI.Xaml.Application>}
	Value	null	WinRT.ObjectReference<WinRT.Interop.IActivationFactoryVftbl>
	_IActivationFactory	null	WinRT.ObjectReference<WinRT.Interop.IActivationFactoryVftbl>
	▶ Static members
	typeNamespace	"Microsoft.UI.Xaml"	string
	typeFullName	"Microsoft.UI.Xaml.Application"	string

To my eye, this looks like _ActivationFactory is null. I am causing this somehow. I am using this library sharpninja/WindowsAppSdkHost to host my application. I don't know what I've neglected in initialization to cause this. My Program.cs looks like this:

namespace VisualParser;

public static class Program
{
    [global::System.Runtime.InteropServices.DllImport("Microsoft.ui.xaml.dll")]
    private static extern void XamlCheckProcessRequirements();

    [STAThread]
    public static Task Main(string[] args)
    {
        XamlCheckProcessRequirements();

        global::WinRT.ComWrappersSupport.InitializeComWrappers();

        return AppHost.StartAsync();
    }

    static Program()
    {
        var builder = new WindowsAppSdkHostBuilder<VisualParserApp>();

        builder.ConfigureLogging(
            logBuilder => logBuilder.AddSimpleConsole()
                .AddEventLog(settings =>
            {
                settings.SourceName = "VisualParser";
                settings.Filter = (msg, logLevel) => logLevel >= LogLevel.Warning;
            }));

        builder.ConfigureServices(
            (_, collection) =>
            {
                // Singletons
                collection.AddSingleton<Theme>();
                collection.AddSingleton<MainWindow>();
                collection.AddSingleton<MainPage>();
                collection.AddSingleton<CanvasPage>();
                collection.AddSingleton<NavigationViewModel>();
                collection.AddSingleton<ExpressionsViewModel>();
                collection.AddSingleton(services =>
                    services.GetRequiredService<CanvasPage>().Canvas);

                // Transient
                collection.AddTransient<List<ExpressionHolder>>();
                collection.AddTransient<ObservableCollection<ExpressionModel>>();
            }
        );

        AppHost = builder.Build();
    }

    public static IHost AppHost { get; private set; }
}

Any help would be appreciated!

Packages in use

    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.1.0-preview1" />
    <PackageReference Include="CommunityToolkit.WinUI.UI.Controls" Version="7.1.2" />
    <PackageReference Include="Microsoft.WindowsAppSDK" Version="1.2.220930.4-preview2" />
    <PackageReference Include="SharpNinja.Extensions.WindowsAppSdkHost" Version="1.2.0" />
    <PackageReference Include="Syncfusion.Grid.WinUI" Version="20.3.0.52" />

Project properties

    <OutputType>WinExe</OutputType>
    <TargetFramework>net7.0-windows10.0.19041.0</TargetFramework>
    <LangVersion>11</LangVersion>
    <TargetPlatformVersion>10.0.19041.0</TargetPlatformVersion>
    <TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>
    <RootNamespace>VisualParser</RootNamespace>
    <ApplicationManifest>app.manifest</ApplicationManifest>
    <Platforms>x86;x64;arm64</Platforms>
    <RuntimeIdentifiers>win10-x86;win10-x64;win10-arm64</RuntimeIdentifiers>
    <UseWinUI>true</UseWinUI>
    <Nullable>Enable</Nullable>
    <ImplicitUsings>Enable</ImplicitUsings>
    <EnableDefaultPageItems>true</EnableDefaultPageItems>
   <DefineConstants>DISABLE_XAML_GENERATED_MAIN;DISABLE_XAML_GENERATED_BREAK_ON_UNHANDLED_EXCEPTION</DefineConstants>

Also, I am not using an App.xaml file. My Application is defined as such.

using Microsoft.UI.Dispatching;

namespace VisualParser.Views;

public partial class VisualParserApp : Application
{
    private static Window? m_window = null;

    private static Window Window => m_window ??=
            Program.AppHost.Services.GetRequiredService<MainWindow>();

    public VisualParserApp()
    {
        var dic = Application.Current?.Resources?.MergedDictionaries;
        if (!dic?.Any(t => t is Microsoft.UI.Xaml.Controls.XamlControlsResources) ?? false)
        {
            Resources.MergedDictionaries
                .Add(new Microsoft.UI.Xaml.Controls.XamlControlsResources());
        }

        var theme = AppHost.Services.GetRequiredService<Theme>();
        Resources.MergedDictionaries
            .Add(theme);
    }

    protected override void OnLaunched(LaunchActivatedEventArgs args)
    {
        Window.Activate();
    }

    public void Dispatch(Action action)
    {
        if (Window.DispatcherQueue.HasThreadAccess)
        {
            action();
            return;
        }
        DispatcherQueueHandler callback = action.Invoke;
        Window.DispatcherQueue.TryEnqueue(callback);
    }

}

Full Stack

System.Private.CoreLib.dll!System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(int errorCode = 0) Line 880
	at /_/src/libraries/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.cs(880)
WinRT.Runtime.dll!WinRT.MarshalString.Pinnable.GetAbi()
WinRT.Runtime.dll!WinRT.MarshalString.GetAbi(ref WinRT.MarshalString.Pinnable p = {WinRT.MarshalString.Pinnable})
Microsoft.WinUI.dll!WinRT.WinrtModule.GetActivationFactory(string runtimeClassId = "Microsoft.UI.Xaml.Application")
Microsoft.WinUI.dll!WinRT.BaseActivationFactory.BaseActivationFactory(string typeNamespace = "Microsoft.UI.Xaml", string typeFullName = "Microsoft.UI.Xaml.Application")
Microsoft.WinUI.dll!WinRT.ActivationFactory<Microsoft.UI.Xaml.Application>.ActivationFactory()
Microsoft.WinUI.dll!WinRT.ActivationFactory<Microsoft.UI.Xaml.Application>.ActivationFactory()
[Native to Managed Transition]
[Managed to Native Transition]
Microsoft.WinUI.dll!WinRT.ActivationFactory<Microsoft.UI.Xaml.Application>.As(System.Guid iid = {System.Guid})
Microsoft.WinUI.dll!Microsoft.UI.Xaml.Application.Make___objRef_global__Microsoft_UI_Xaml_IApplicationStatics()
Microsoft.WinUI.dll!Microsoft.UI.Xaml.Application._objRef_global__Microsoft_UI_Xaml_IApplicationStatics.get()
Microsoft.WinUI.dll!Microsoft.UI.Xaml.Application.Start(Microsoft.UI.Xaml.ApplicationInitializationCallback callback = {Method = {System.Reflection.RuntimeMethodInfo}})
CommunityToolkit.Extensions.Hosting.WindowsAppSdk.dll!CommunityToolkit.Extensions.Hosting.WindowsAppSdkHost<VisualParser.Views.VisualParserApp>.StartAsync(System.Threading.CancellationToken cancellationToken = IsCancellationRequested = false)
VisualParser.dll!VisualParser.Program.Main(string[] args = {string[0]}) Line 15
	at C:\GitHub\GPS\VisualParser\VisualParser\VisualParser\Program.cs(15)
VisualParser.dll!VisualParser.Program.<Main>(string[] args = {string[0]})
[Native to Managed Transition]
[Inline Frame] hostpolicy.dll!coreclr_t::execute_assembly(int) Line 89
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\coreclr.cpp(89)
hostpolicy.dll!run_app_for_context(const hostpolicy_context_t & context={...}, int argc=0, const wchar_t * * argv) Line 255
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\hostpolicy.cpp(255)
hostpolicy.dll!run_app(const int argc=0, const wchar_t * * argv=0x00000158c060bc08) Line 284
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\hostpolicy.cpp(284)
hostpolicy.dll!corehost_main(const int argc=1, const wchar_t * * argv=0x00000158c060bc00) Line 430
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\hostpolicy.cpp(430)
hostfxr.dll!execute_app(const std::wstring & impl_dll_dir, corehost_init_t * init=0x00000158c061c7e0, const int argc=1, const wchar_t * * argv=0x00000158c060bc00) Line 146
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(146)
hostfxr.dll!`anonymous namespace'::read_config_and_execute(const std::wstring & host_command={...}, const host_startup_info_t & host_info, const std::wstring & app_candidate, const std::unordered_map<enum known_options,std::vector<std::wstring,std::allocator<std::wstring>>,known_options_hash,std::equal_to<enum known_options>,std::allocator<std::pair<enum known_options const ,std::vector<std::wstring,std::allocator<std::wstring>>>>> & opts, int new_argc=1, const wchar_t * * new_argv=0x00000158c060bc00, host_mode_t mode=apphost, const bool is_sdk_command=false, wchar_t * out_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 533
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(533)
hostfxr.dll!fx_muxer_t::handle_exec_host_command(const std::wstring & host_command={...}, const host_startup_info_t & host_info={...}, const std::wstring & app_candidate={...}, const std::unordered_map<enum known_options,std::vector<std::wstring,std::allocator<std::wstring>>,known_options_hash,std::equal_to<enum known_options>,std::allocator<std::pair<enum known_options const ,std::vector<std::wstring,std::allocator<std::wstring>>>>> & opts={...}, int argc=1, const wchar_t * * argv=0x00000158c060bc00, int argoff=1, host_mode_t mode=apphost, const bool is_sdk_command=false, wchar_t * result_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 1018
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(1018)
hostfxr.dll!fx_muxer_t::execute(const std::wstring host_command={...}, const int argc=1, const wchar_t * * argv=0x00000158c060bc00, const host_startup_info_t & host_info={...}, wchar_t * result_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 579
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(579)
hostfxr.dll!hostfxr_main_startupinfo(const int argc=1, const wchar_t * * argv=0x00000158c060bc00, const wchar_t * host_path=0x00000158c060ac90, const wchar_t * dotnet_root=0x00000158c0616050, const wchar_t * app_path=0x00000158c061af70) Line 61
	at D:\a\_work\1\s\src\native\corehost\fxr\hostfxr.cpp(61)
VisualParser.exe!exe_start(const int argc=1, const wchar_t * * argv=0x00000158c060bc00) Line 251
	at D:\a\_work\1\s\src\native\corehost\corehost.cpp(251)
VisualParser.exe!wmain(const int argc, const wchar_t * * argv=0x00000158c060bc00) Line 322
	at D:\a\_work\1\s\src\native\corehost\corehost.cpp(322)
[Inline Frame] VisualParser.exe!invoke_main() Line 90
	at D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl(90)
VisualParser.exe!__scrt_common_main_seh() Line 288
	at D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl(288)
kernel32.dll!BaseThreadInitThunk()
ntdll.dll!RtlUserThreadStart�()

[manodasanW]

@sharpninja Can you comment on what is the exception / error you are seeing? Looking at the above stack, it looks like the native call to get the activation factory hasn't happened yet. It is on this line calling MarshalString.GetAbi whose result would be passed as a parameter. And based on the stack, it looks like that Marshal.ThrowExceptionForHR call which you had a breakpoint on didn't fail given the parameter in the call stack says errorCode = 0. It would be interesting after that call, when it does Platform.RoGetActivationFactory whether that fails or not. It is only after that when the _IActivationFactory and so on will get set.

[sharpninja]

@sharpninja Can you comment on what is the exception / error you are seeing? Looking at the above stack, it looks like the native call to get the activation factory hasn't happened yet. It is on this line calling MarshalString.GetAbi whose result would be passed as a parameter. And based on the stack, it looks like that Marshal.ThrowExceptionForHR call which you had a breakpoint on didn't fail given the parameter in the call stack says errorCode = 0. It would be interesting after that call, when it does Platform.RoGetActivationFactory whether that fails or not. It is only after that when the _IActivationFactory and so on will get set.

Letting the code run past the break point ends with this error:

System.Runtime.InteropServices.COMException
  HResult=0x8000FFFF
  Message=Catastrophic failure (0x8000FFFF (E_UNEXPECTED))
  Source=WinRT.Runtime
  StackTrace:
   at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|20_0(Int32 hr)

Call stack

WinRT.Runtime.dll!WinRT.ExceptionHelpers.ThrowExceptionForHR.__Throw|20_0(int hr = -2147418113)
WinRT.Runtime.dll!WinRT.ExceptionHelpers.ThrowExceptionForHR(int hr = -2147418113)
Microsoft.WinUI.dll!ABI.Microsoft.UI.Xaml.IApplicationMethods.get_Resources(WinRT.IObjectReference _obj = {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>})
Microsoft.WinUI.dll!Microsoft.UI.Xaml.Application.Resources.get()
VisualParser.dll!VisualParser.Views.VisualParserApp.VisualParserApp() Line 14
	at C:\GitHub\GPS\VisualParser\VisualParser\VisualParser\Views\VisualParserApp.cs(14)
[Native to Managed Transition]
[Managed to Native Transition]
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(Microsoft.Extensions.DependencyInjection.ServiceLookup.ConstructorCallSite constructorCallSite = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ConstructorCallSite}, Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext context = {Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext}) Line 61
	at Microsoft.Extensions.DependencyInjection.ServiceLookup\CallSiteRuntimeResolver.cs(61)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor<Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext, object>.VisitCallSiteMain(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite callSite = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ConstructorCallSite}, Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext argument = {Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext}) Line 34
	at Microsoft.Extensions.DependencyInjection.ServiceLookup\CallSiteVisitor.cs(34)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite callSite = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ConstructorCallSite}, Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext context = {Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext}) Line 85
	at Microsoft.Extensions.DependencyInjection.ServiceLookup\CallSiteRuntimeResolver.cs(85)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor<Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext, object>.VisitCallSite(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite callSite = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ConstructorCallSite}, Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext argument = {Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext}) Line 21
	at Microsoft.Extensions.DependencyInjection.ServiceLookup\CallSiteVisitor.cs(21)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceCallSite callSite = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ConstructorCallSite}, Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope scope = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope}) Line 35
	at Microsoft.Extensions.DependencyInjection.ServiceLookup\CallSiteRuntimeResolver.cs(35)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateServiceAccessor(System.Type serviceType = {Name = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context. FullName = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context.}) Line 179
	at Microsoft.Extensions.DependencyInjection\ServiceProvider.cs(179)
System.Collections.Concurrent.dll!System.Collections.Concurrent.ConcurrentDictionary<System.Type, System.Func<Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope, object>>.GetOrAdd(System.Type key = {Name = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context. FullName = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context.}, System.Func<System.Type, System.Func<Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope, object>> valueFactory) Line 1152
	at /_/src/libraries/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentDictionary.cs(1152)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(System.Type serviceType = {Name = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context. FullName = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context.}, Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope serviceProviderEngineScope = {Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope}) Line 136
	at Microsoft.Extensions.DependencyInjection\ServiceProvider.cs(136)
Microsoft.Extensions.DependencyInjection.dll!Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(System.Type serviceType = {Name = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context. FullName = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context.}) Line 99
	at Microsoft.Extensions.DependencyInjection\ServiceProvider.cs(99)
Microsoft.Extensions.DependencyInjection.Abstractions.dll!Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(System.IServiceProvider provider = {Microsoft.Extensions.DependencyInjection.ServiceProvider}, System.Type serviceType = {Name = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context. FullName = Inspecting the state of an object in the debuggee of type System.Type is not supported in this context.}) Line 55
	at /_/src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ServiceProviderServiceExtensions.cs(55)
Microsoft.Extensions.DependencyInjection.Abstractions.dll!Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService<VisualParser.Views.VisualParserApp>(System.IServiceProvider provider = {Microsoft.Extensions.DependencyInjection.ServiceProvider}) Line 78
	at /_/src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ServiceProviderServiceExtensions.cs(78)
CommunityToolkit.Extensions.Hosting.WindowsAppSdk.dll!CommunityToolkit.Extensions.Hosting.WindowsAppSdkHost<VisualParser.Views.VisualParserApp>.StartAsync.AnonymousMethod__1(Microsoft.UI.Xaml.ApplicationInitializationCallbackParams _ = {Microsoft.UI.Xaml.ApplicationInitializationCallbackParams})
Microsoft.WinUI.dll!ABI.Microsoft.UI.Xaml.ApplicationInitializationCallback.Do_Abi_Invoke(nint thisPtr, nint p)
[Native to Managed Transition]
Microsoft.ui.xaml.dll!DllGetActivationFactory() + 14014 bytes
Microsoft.ui.xaml.dll!DllGetActivationFactory() + 12542 bytes
[Managed to Native Transition]
Microsoft.WinUI.dll!ABI.Microsoft.UI.Xaml.IApplicationStaticsMethods.Start(WinRT.IObjectReference _obj = {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}, Microsoft.UI.Xaml.ApplicationInitializationCallback callback = {Method = {System.Reflection.RuntimeMethodInfo}})
Microsoft.WinUI.dll!Microsoft.UI.Xaml.Application.Start(Microsoft.UI.Xaml.ApplicationInitializationCallback callback = {Method = {System.Reflection.RuntimeMethodInfo}})
CommunityToolkit.Extensions.Hosting.WindowsAppSdk.dll!CommunityToolkit.Extensions.Hosting.WindowsAppSdkHost<VisualParser.Views.VisualParserApp>.StartAsync(System.Threading.CancellationToken cancellationToken = IsCancellationRequested = false)
VisualParser.dll!VisualParser.Program.Main(string[] args = {string[0]}) Line 15
	at C:\GitHub\GPS\VisualParser\VisualParser\VisualParser\Program.cs(15)
VisualParser.dll!VisualParser.Program.<Main>(string[] args = {string[0]})
[Native to Managed Transition]
[Inline Frame] hostpolicy.dll!coreclr_t::execute_assembly(int) Line 89
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\coreclr.cpp(89)
hostpolicy.dll!run_app_for_context(const hostpolicy_context_t & context={...}, int argc=0, const wchar_t * * argv) Line 255
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\hostpolicy.cpp(255)
hostpolicy.dll!run_app(const int argc=0, const wchar_t * * argv=0x000002360cc0bbd8) Line 284
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\hostpolicy.cpp(284)
hostpolicy.dll!corehost_main(const int argc=1, const wchar_t * * argv=0x000002360cc0bbd0) Line 430
	at D:\a\_work\1\s\src\native\corehost\hostpolicy\hostpolicy.cpp(430)
hostfxr.dll!execute_app(const std::wstring & impl_dll_dir, corehost_init_t * init=0x000002360cc1c5d0, const int argc=1, const wchar_t * * argv=0x000002360cc0bbd0) Line 146
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(146)
hostfxr.dll!`anonymous namespace'::read_config_and_execute(const std::wstring & host_command={...}, const host_startup_info_t & host_info, const std::wstring & app_candidate, const std::unordered_map<enum known_options,std::vector<std::wstring,std::allocator<std::wstring>>,known_options_hash,std::equal_to<enum known_options>,std::allocator<std::pair<enum known_options const ,std::vector<std::wstring,std::allocator<std::wstring>>>>> & opts, int new_argc=1, const wchar_t * * new_argv=0x000002360cc0bbd0, host_mode_t mode=apphost, const bool is_sdk_command=false, wchar_t * out_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 533
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(533)
hostfxr.dll!fx_muxer_t::handle_exec_host_command(const std::wstring & host_command={...}, const host_startup_info_t & host_info={...}, const std::wstring & app_candidate={...}, const std::unordered_map<enum known_options,std::vector<std::wstring,std::allocator<std::wstring>>,known_options_hash,std::equal_to<enum known_options>,std::allocator<std::pair<enum known_options const ,std::vector<std::wstring,std::allocator<std::wstring>>>>> & opts={...}, int argc=1, const wchar_t * * argv=0x000002360cc0bbd0, int argoff=1, host_mode_t mode=apphost, const bool is_sdk_command=false, wchar_t * result_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 1018
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(1018)
hostfxr.dll!fx_muxer_t::execute(const std::wstring host_command={...}, const int argc=1, const wchar_t * * argv=0x000002360cc0bbd0, const host_startup_info_t & host_info={...}, wchar_t * result_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 579
	at D:\a\_work\1\s\src\native\corehost\fxr\fx_muxer.cpp(579)
hostfxr.dll!hostfxr_main_startupinfo(const int argc=1, const wchar_t * * argv=0x000002360cc0bbd0, const wchar_t * host_path=0x000002360cc0d210, const wchar_t * dotnet_root=0x000002360cc166d0, const wchar_t * app_path=0x000002360cc2d700) Line 61
	at D:\a\_work\1\s\src\native\corehost\fxr\hostfxr.cpp(61)
VisualParser.exe!exe_start(const int argc=1, const wchar_t * * argv=0x000002360cc0bbd0) Line 251
	at D:\a\_work\1\s\src\native\corehost\corehost.cpp(251)
VisualParser.exe!wmain(const int argc, const wchar_t * * argv=0x000002360cc0bbd0) Line 322
	at D:\a\_work\1\s\src\native\corehost\corehost.cpp(322)
[Inline Frame] VisualParser.exe!invoke_main() Line 90
	at D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl(90)
VisualParser.exe!__scrt_common_main_seh() Line 288
	at D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl(288)
kernel32.dll!BaseThreadInitThunk()
ntdll.dll!RtlUserThreadStart�()

Local Variables

	Name	Value	Type
▶	$exception	{"Catastrophic failure (0x8000FFFF (E_UNEXPECTED))"}	System.Runtime.InteropServices.COMException
◢	this	{VisualParser.Views.VisualParserApp}	VisualParser.Views.VisualParserApp
	DebugSettings	Function evaluation disabled because a previous function evaluation timed out. You must continue execution to reenable function evaluation.	Microsoft.UI.Xaml.DebugSettings
	FocusVisualKind	Function evaluation disabled because a previous function evaluation timed out. You must continue execution to reenable function evaluation.	Microsoft.UI.Xaml.FocusVisualKind
	HighContrastAdjustment	Function evaluation disabled because a previous function evaluation timed out. You must continue execution to reenable function evaluation.	Microsoft.UI.Xaml.ApplicationHighContrastAdjustment
	RequestedTheme	Function evaluation disabled because a previous function evaluation timed out. You must continue execution to reenable function evaluation.	Microsoft.UI.Xaml.ApplicationTheme
	Resources	Function evaluation disabled because a previous function evaluation timed out. You must continue execution to reenable function evaluation.	Microsoft.UI.Xaml.ResourceDictionary
	ThisPtr	0x00000276a3ee16d0	System.IntPtr
	▶ WinRT.IWinRTObject.AdditionalTypeData	Count = 0	System.Collections.Concurrent.ConcurrentDictionary<System.RuntimeTypeHandle, object>
	WinRT.IWinRTObject.HasUnwrappableNativeObject	false	bool
	▶ WinRT.IWinRTObject.NativeObject	{WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}	WinRT.IObjectReference {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}
	▶ WinRT.IWinRTObject.QueryInterfaceCache	Count = 0	System.Collections.Concurrent.ConcurrentDictionary<System.RuntimeTypeHandle, WinRT.IObjectReference>
	▶ ___objRef_global__Microsoft_UI_Xaml_IApplication	{WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}	WinRT.IObjectReference {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}
	___objRef_global__Microsoft_UI_Xaml_IApplicationOverrides	null	WinRT.IObjectReference
	▶ _additionalTypeData	null	System.Collections.Concurrent.ConcurrentDictionary<System.RuntimeTypeHandle, object>
	_default	null	Microsoft.UI.Xaml.IApplication
	▶ _inner	{WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}	WinRT.IObjectReference {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}
	▶ _objRef_global__Microsoft_UI_Xaml_IApplication	{WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}	WinRT.IObjectReference {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}
	_objRef_global__Microsoft_UI_Xaml_IApplicationOverrides	Function evaluation disabled because a previous function evaluation timed out. You must continue execution to reenable function evaluation.	WinRT.IObjectReference
	▶ _queryInterfaceCache	null	System.Collections.Concurrent.ConcurrentDictionary<System.RuntimeTypeHandle, WinRT.IObjectReference>
	▶ Static members
	dic	null	System.Collections.Generic.IList<Microsoft.UI.Xaml.ResourceDictionary>
	theme	null	VisualParser.Views.Theme

[sharpninja]

Letting the app continue from this error, it does eventually start and when it attempts to add a TextBox to a Panel, an error (HR -2147467259) is sent to ThrowExceptionForHR with this call stack:

>	System.Private.CoreLib.dll!System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(int errorCode = -2147467259) Line 882	C#	Symbols loaded.
 	WinRT.Runtime.dll!WinRT.DelegateExtensions.DynamicInvokeAbi(System.Delegate del = {Method = <Internal Error evaluating expression>}, object[] invoke_params = {object[2]})	Unknown	No symbols loaded.
 	WinRT.Runtime.dll!ABI.System.Collections.Generic.IVectorMethods<Microsoft.UI.Xaml.UIElement>.Append(WinRT.IObjectReference obj = {WinRT.ObjectReference<ABI.System.Collections.Generic.IList<Microsoft.UI.Xaml.UIElement>.Vftbl>}, Microsoft.UI.Xaml.UIElement value = {Microsoft.UI.Xaml.Controls.TextBox})	Unknown	No symbols loaded.
 	WinRT.Runtime.dll!ABI.System.Collections.Generic.IListMethods<Microsoft.UI.Xaml.UIElement>.Add(WinRT.IObjectReference obj = {WinRT.ObjectReference<ABI.System.Collections.Generic.IList<Microsoft.UI.Xaml.UIElement>.Vftbl>}, Microsoft.UI.Xaml.UIElement item = {Microsoft.UI.Xaml.Controls.TextBox})	Unknown	No symbols loaded.
 	Microsoft.WinUI.dll!Microsoft.UI.Xaml.Controls.UIElementCollection.Add(Microsoft.UI.Xaml.UIElement item = {Microsoft.UI.Xaml.Controls.TextBox})	Unknown	No symbols loaded.
 	VisualParser.dll!VisualParser.Views.CanvasPage.Expressions_CollectionChanged(object sender = Count = 1, System.Collections.Specialized.NotifyCollectionChangedEventArgs e = {System.Collections.Specialized.NotifyCollectionChangedEventArgs}) Line 64	C#	Symbols loaded.
 	System.ObjectModel.dll!System.Collections.ObjectModel.ObservableCollection<VisualParser.Models.ExpressionModel>.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) Line 192	C#	Symbols loaded.
 	VisualParser.dll!VisualParser.ViewModels.ExpressionsViewModel.AddExpression(object _ = null) Line 41	C#	Symbols loaded.
 	VisualParser.dll!VisualParser.Views.MainPage.AddExpression() Line 56	C#	Symbols loaded.
 	CommunityToolkit.Mvvm.dll!CommunityToolkit.Mvvm.Input.RelayCommand.Execute(object parameter = null)	Unknown	No symbols loaded.
 	WinRT.Runtime.dll!ABI.System.Windows.Input.ICommand.Vftbl.Do_Abi_Execute_3(nint thisPtr, nint parameter)	Unknown	No symbols loaded.
 	[Native to Managed Transition]		Annotated Frame
 	Microsoft.ui.xaml.dll!00007ff83bc06faa()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83bc07380()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83bc8e82c()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83bbfd0e1()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83bc088e2()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83bc0865b()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b60a2dd()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b503e86()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b5041bb()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b503f8d()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b557a81()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b43edf3()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b43eb49()	Unknown	No symbols loaded.
 	user32.dll!UserCallWinProcCheckWow()	Unknown	Symbols loaded.
 	user32.dll!DispatchClientMessage()	Unknown	Symbols loaded.
 	user32.dll!__fnDWORD�()	Unknown	Symbols loaded.
 	ntdll.dll!KiUserCallbackDispatcherContinue�()	Unknown	Symbols loaded.
 	win32u.dll!NtUserMessageCall�()	Unknown	Symbols loaded.
 	user32.dll!SendMessageWorker()	Unknown	Symbols loaded.
 	user32.dll!SendMessageW()	Unknown	Symbols loaded.
 	Microsoft.VisualStudio.Debugger.Runtime.Impl.dll!InitRuntimeDllImpl() + 987 bytes	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b5479a8()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b496352()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b495b45()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b5288d3()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b52870a()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b5285b9()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b528568()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b5283fb()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b621654()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa1a0af()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa1a015()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa19e35()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa19ab7()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa199ce()	Unknown	No symbols loaded.
 	ninput.dll!00007ff896998c5c()	Unknown	No symbols loaded.
 	ninput.dll!StopInteractionContext() + 5070 bytes	Unknown	No symbols loaded.
 	ninput.dll!00007ff8969b18f0()	Unknown	No symbols loaded.
 	ninput.dll!00007ff8969b18b6()	Unknown	No symbols loaded.
 	ninput.dll!00007ff8969b0ffa()	Unknown	No symbols loaded.
 	ninput.dll!00007ff8969b10d2()	Unknown	No symbols loaded.
 	ninput.dll!00007ff8969af51c()	Unknown	No symbols loaded.
 	ninput.dll!StopInteractionContext() + 7524 bytes	Unknown	No symbols loaded.
 	ninput.dll!StopInteractionContext() + 5831 bytes	Unknown	No symbols loaded.
 	ninput.dll!ProcessBufferedPacketsInteractionContext() + 60 bytes	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa1a435()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b543c41()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b4fc154()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b4fc402()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b3f4869()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b3f3719()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b3f34f9()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b3f6baa()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83bb54c8d()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b7aaab2()	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!00007ff83b7ab2e6()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa06bd5()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa09dea()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa06f75()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa0654c()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa09ccd()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa097b2()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa0968f()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa0b84c()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa2321d()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!CoreUICallReceive() + 167 bytes	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa1394f()	Unknown	No symbols loaded.
 	Microsoft.UI.Input.dll!00007ff83aa22bf3()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b9c6d8()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b9c045()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b9c8b2()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857baf6ae()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857be2346()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b8ace4()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b8317d()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b82ec7()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857ba8c26()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b7252f()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857ba82f4()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857bc364c()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b79e64()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b7971c()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b6ee77()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b71138()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b715e7()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857b714d8()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857bb75ad()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857bb7532()	Unknown	No symbols loaded.
 	CoreMessagingXP.dll!00007ff857bb73e3()	Unknown	No symbols loaded.
 	user32.dll!UserCallWinProcCheckWow()	Unknown	Symbols loaded.
 	user32.dll!DispatchClientMessage()	Unknown	Symbols loaded.
 	user32.dll!__fnDWORD�()	Unknown	Symbols loaded.
 	ntdll.dll!KiUserCallbackDispatcherContinue�()	Unknown	Symbols loaded.
 	win32u.dll!NtUserGetMessage�()	Unknown	Symbols loaded.
 	user32.dll!GetMessageW()	Unknown	Symbols loaded.
 	Microsoft.ui.xaml.dll!DllGetActivationFactory() + 12058 bytes	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!DllGetActivationFactory() + 14188 bytes	Unknown	No symbols loaded.
 	Microsoft.ui.xaml.dll!DllGetActivationFactory() + 12542 bytes	Unknown	No symbols loaded.
 	[Managed to Native Transition]		Annotated Frame
 	Microsoft.WinUI.dll!ABI.Microsoft.UI.Xaml.IApplicationStaticsMethods.Start(WinRT.IObjectReference _obj = {WinRT.ObjectReference<WinRT.Interop.IUnknownVftbl>}, Microsoft.UI.Xaml.ApplicationInitializationCallback callback = {Method = {System.Reflection.RuntimeMethodInfo}})	Unknown	No symbols loaded.
 	Microsoft.WinUI.dll!Microsoft.UI.Xaml.Application.Start(Microsoft.UI.Xaml.ApplicationInitializationCallback callback = {Method = {System.Reflection.RuntimeMethodInfo}})	Unknown	No symbols loaded.
 	CommunityToolkit.Extensions.Hosting.WindowsAppSdk.dll!CommunityToolkit.Extensions.Hosting.WindowsAppSdkHost<VisualParser.Views.VisualParserApp>.StartAsync(System.Threading.CancellationToken cancellationToken = IsCancellationRequested = false)	C#	Symbols loaded.
 	VisualParser.dll!VisualParser.Program.Main(string[] args = {string[0]}) Line 15	C#	Symbols loaded.
 	VisualParser.dll!VisualParser.Program.<Main>(string[] args = {string[0]})	Unknown	Symbols loaded.
 	[Native to Managed Transition]		Annotated Frame
 	[Inline Frame] hostpolicy.dll!coreclr_t::execute_assembly(int) Line 89	C++	Symbols loaded.
 	hostpolicy.dll!run_app_for_context(const hostpolicy_context_t & context={...}, int argc=0, const wchar_t * * argv) Line 255	C++	Symbols loaded.
 	hostpolicy.dll!run_app(const int argc=0, const wchar_t * * argv=0x000002233740bbd8) Line 284	C++	Symbols loaded.
 	hostpolicy.dll!corehost_main(const int argc=1, const wchar_t * * argv=0x000002233740bbd0) Line 430	C++	Symbols loaded.
 	hostfxr.dll!execute_app(const std::wstring & impl_dll_dir, corehost_init_t * init=0x000002233741c5d0, const int argc=1, const wchar_t * * argv=0x000002233740bbd0) Line 146	C++	Symbols loaded.
 	hostfxr.dll!`anonymous namespace'::read_config_and_execute(const std::wstring & host_command={...}, const host_startup_info_t & host_info, const std::wstring & app_candidate, const std::unordered_map<enum known_options,std::vector<std::wstring,std::allocator<std::wstring>>,known_options_hash,std::equal_to<enum known_options>,std::allocator<std::pair<enum known_options const ,std::vector<std::wstring,std::allocator<std::wstring>>>>> & opts, int new_argc=1, const wchar_t * * new_argv=0x000002233740bbd0, host_mode_t mode=apphost, const bool is_sdk_command=false, wchar_t * out_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 533	C++	Symbols loaded.
 	hostfxr.dll!fx_muxer_t::handle_exec_host_command(const std::wstring & host_command={...}, const host_startup_info_t & host_info={...}, const std::wstring & app_candidate={...}, const std::unordered_map<enum known_options,std::vector<std::wstring,std::allocator<std::wstring>>,known_options_hash,std::equal_to<enum known_options>,std::allocator<std::pair<enum known_options const ,std::vector<std::wstring,std::allocator<std::wstring>>>>> & opts={...}, int argc=1, const wchar_t * * argv=0x000002233740bbd0, int argoff=1, host_mode_t mode=apphost, const bool is_sdk_command=false, wchar_t * result_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 1018	C++	Symbols loaded.
 	hostfxr.dll!fx_muxer_t::execute(const std::wstring host_command={...}, const int argc=1, const wchar_t * * argv=0x000002233740bbd0, const host_startup_info_t & host_info={...}, wchar_t * result_buffer=0x0000000000000000, int buffer_size=0, int * required_buffer_size=0x0000000000000000) Line 579	C++	Symbols loaded.
 	hostfxr.dll!hostfxr_main_startupinfo(const int argc=1, const wchar_t * * argv=0x000002233740bbd0, const wchar_t * host_path=0x000002233740d210, const wchar_t * dotnet_root=0x0000022337416090, const wchar_t * app_path=0x000002233742dca0) Line 61	C++	Symbols loaded.
 	VisualParser.exe!exe_start(const int argc=1, const wchar_t * * argv=0x000002233740bbd0) Line 251	C++	Symbols loaded.
 	VisualParser.exe!wmain(const int argc, const wchar_t * * argv=0x000002233740bbd0) Line 322	C++	Symbols loaded.
 	[Inline Frame] VisualParser.exe!invoke_main() Line 90	C++	Symbols loaded.
 	VisualParser.exe!__scrt_common_main_seh() Line 288	C++	Symbols loaded.
 	kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
 	ntdll.dll!RtlUserThreadStart�()	Unknown	Symbols loaded.

So it is failing at

WinRT.Runtime.dll!ABI.System.Collections.Generic.IVectorMethods<Microsoft.UI.Xaml.UIElement>.Append(WinRT.IObjectReference obj = {WinRT.ObjectReference<ABI.System.Collections.Generic.IList<Microsoft.UI.Xaml.UIElement>.Vftbl>}, Microsoft.UI.Xaml.UIElement value = {Microsoft.UI.Xaml.Controls.TextBox})	Unknown	No symbols loaded.

After that it goes into the error handling code.

[sharpninja]

I have more findings to post, but a brief summary is that without loading the XAML from App.xaml, the App.Current.Resources is null, and trying to instantiate a ResourceDictionary manually and assigning it to App.Current.Rsources results in a COM Exception with a description of "FAIL".

[ghost]

...but a brief summary is that without loading the XAML from App.xaml, the App.Current.Resources is null, and trying to instantiate a ResourceDictionary manually and assigning it to App.Current.Rsources results in a COM Exception...

#2926

dotnet/maui#8413 (comment)

these two threads are related.
reading them up may help.