XAudio native library loading error on UWP (preview) on .NET9

[andrew-kulikov]

Hi!

I'm trying to migrate an UWP application to .NET 9 according to this guide. As part of migration process we decided to migrate from SharpDX to Vortice as it's more modern and NativeAOT friendly.

First I tried to migrate XAudio2 and found a problem with native library (xaudio2_9.dll) loading on UWP. When I try to instanciate an IXAudio2 via _device = XAudio2.XAudio2Create();, it fails with such error message:

System.TypeInitializationException
  HResult=0x80131534
  Message=The type initializer for 'Vortice.XAudio2.XAudio2Native' threw an exception.
  Source=Vortice.XAudio2
  StackTrace:
   at Vortice.XAudio2.XAudio2Native.XAudio2Create(ProcessorSpecifier processorSpecifier, IntPtr& nativePtr)
   at Vortice.XAudio2.IXAudio2..ctor(ProcessorSpecifier processorSpecifier, Boolean registerCallback)
   at Vortice.XAudio2.XAudio2.XAudio2Create(ProcessorSpecifier processorSpecifier, Boolean registerCallback)
   at UwpApp.XAudioDevice..ctor() in C:\repos\vortice-uwp-dotnet\UwpApp\XAudioDevice.cs:line 23

  This exception was originally thrown at this call stack:
    System.ArgumentNullException.Throw(string)
    System.Runtime.InteropServices.NativeLibrary.GetExport(nint, string)
    Vortice.XAudio2.XAudio2Native.GetExport(string)
    Vortice.XAudio2.XAudio2Native.XAudio2Native()

Inner Exception 1:
ArgumentNullException: Value cannot be null. (Parameter 'handle')

I checked source code, and found that XAudio2Native calls NativeLibrary.TryLoad method, which returs IntPtr.Zero. But if I use another overload of TryLoad manually, it works fine, and following calls to the library also work:

NativeLibrary.TryLoad("xaudio2_9.dll", Assembly.GetExecutingAssembly(), DllImportSearchPath.LegacyBehavior, out var handle);
_device = XAudio2.XAudio2Create();

I also checked exatly the same code on WinUI 3 with the same target framework net9.0-windows10.0.26100.0, and it works fine. Repository with both samples can be found here: https://github.com/andrew-kulikov/vortice-uwp-dotnet.

So there are few questions regarding this:

1. Are you planning to support UWP on .net9+?
2. Is that a problem on dotnet runtime side?
3. Are there any workarounds except manual call to NativeLibrary.TryLoad?