uwp-desktop: The type forwarder for type 'Windows.Foundation.IAsyncOperation`1' in assembly 'Windows' causes a cycle

I’d like to use await with IAsyncOperation. after I added

c:\Program Files (x86)\Windows Kits\10\UnionMetadata\Facade\Windows.WinMD
c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETCore\v4.5\System.Runtime.WindowsRuntime.dll

I got:

The type forwarder for type 'Windows.Foundation.IAsyncOperation`1' in assembly 'Windows' causes a cycle

About this issue

Original URL
State: open
Created 8 years ago
Reactions: 1
Comments: 15

Most upvoted comments

@JamesEarle @bao-qian the instructions in this repo and on the nuget site are wrong. You do not manually add the facade for the API you need. This is what causes the circular reference.

You simply add the full Windows.winmd at C:\Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.16299.0\Windows.winmd and System.Runtime.WindowsRuntime. That’s it. Note when I say “full”, I mean the .winmd file should be a few megabytes. There’s plenty of them with the same name sprinkled around that are a few kb and it’s easy to screw up and select one of these.

Then, wherever you call await on an IAsyncOperation, make sure you have using System; in the same source file.

Hope this helps people.

+10

TechnikEmpire on Apr 15, 2018

This issue is currently crushing my hopes and dreams.

TechnikEmpire on Mar 9, 2018

@TechnikEmpire Thank you for clarifying this! I had previously added the “Target Platform = 10” in the .csproj file, then added the UWP references as needed and hit the circular reference issue. Simply doing the two things you recommended fixed the issues (including getting the right version of the .winmd file).

duncanmacmichael on Apr 15, 2018