Calling UWP from .NET Core 2.0

[nesherhh]

Is it possible to call Windows 10 APIs (UWP) from a .NET Core 2.0 App?
It does work from .NET Framework 4.7, but not from .NET Core 2.0.
I'm getting this exception at runtime:

System.TypeLoadException: Could not load type 'System.Threading.Tasks.AsyncCausalityTracer' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
   at System.Threading.Tasks.AsyncInfoToTaskBridge`2..ctor(CancellationToken cancellationToken)
   at System.WindowsRuntimeSystemExtensions.AsTask[TResult](IAsyncOperation`1 source, CancellationToken cancellationToken)
   at System.WindowsRuntimeSystemExtensions.AsTask[TResult](IAsyncOperation`1 source)
   at System.WindowsRuntimeSystemExtensions.GetAwaiter[TResult](IAsyncOperation`1 source)
   at ClassLibrary1.Class1.<Abc>d__0.MoveNext() in c:\tmp\ConsoleApp1\ClassLibrary1\Class1.cs:line 12
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at ConsoleApp1.Program.<Main>d__0.MoveNext() in c:\tmp\ConsoleApp1\ConsoleApp1\Program.cs:line 16

[richlander]

PTAL @weshaggard @terrajobst @Petermarcu

[iamcarbon]

Do we know if a fix is landing in .NETCORE 2.1?

[cfeilen]

Also hitting this.

[iamcarbon]

Any update from the team?

[matt1va]

This also repro'd for me when building the .NET Core app targeting 2.1

[MaxxDelusional]

I can confirm. This is not working in 2.1.

I only received this error after adding the System.Runtime.WindowsRuntime nuget package. I can't seem to find a version of this assembly that will allow me use UWP APIs in my dotnetcore console app.

[andriysavin]

Looks like an artificial limitation. Since UWP apis can be called from .net core if not using async/await infrastructure, it's only a matter of porting System.Runtime.WindowsRuntime to this runtime. I hate sticking to full framework just because of this library. Any hope on this?

[andriysavin]

Looks like some work on this is happening here https://github.com/dotnet/corefx/issues/22789

[luqunl]

@jeffschwMSFT , @richlander

[dlech]

FWIW, I had success calling UWP Bluetooth LE APIs from a netcoreapp3.0 using .NET Core 3.0 preview 1.

[jeffschwMSFT]

@dlech I am happy to hear that our newly enabled support in .NET Core 3.0 is working for you. At this point we do not have any plans on moving this support to .NET Core 2.*.

[GiancarloLelli]

Hello @dlech - any chance you could share how you did that?

[jeffschwMSFT]

@GiancarloLelli around Preview 2 we plan on having a sample that demonstrates how to build such an app. There are a few things you need to add to your project file (manually right now) and it should work.
From an existing netcoreapp3.0 you can add the following to your project file:

  <ItemGroup>
    <Reference Include="Windows">
      <HintPath><insert full path>\Windows.winmd</HintPath>
    </Reference>
  </ItemGroup>

Add the necessary nuget packages:
dotnet add package System.Runtime.WindowsRuntime --version 4.6.0-preview.18571.3
And possibly:
dotnet add package System.Runtime.WindowsRuntime.UI.Xaml --version 4.6.0-preview.18571.3

[GiancarloLelli]

Hi @jeffschwMSFT - apparently after digging a little on GitHub and the web I came up with the same solution you mentioned. I've successfully started a BLE Advertisement from a .NET Core 3.0 console app.
Thanks for the feedback though :) I'm really looking forward for an official guidance - in case you need any help writing it, I would be happy to help!