Runtime: Windows Compat Pack: Could not load type System.Runtime.CompilerServices.IAsyncStateMachine

[joshfree]

Original issue https://github.com/dotnet/core/issues/1276

_@xs2bharat commented on Feb 22_

Getting error "Could not load type 'System.Runtime.CompilerServices.IAsyncStateMachine' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'"

Issue Title

Getting error "Could not load type 'System.Runtime.CompilerServices.IAsyncStateMachine' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'"

General

I am using .net core 2.0 framework to design asp.net web api and using Microsoft.Windows.Compatibility pack to port few internally designed library

_@BetsyOstrander commented on Feb 27_
I am getting this too. No error until I added a .net standard lib for accessing Active Directory, which includes the Windows Compatibility pack.

_@CarlosOnline commented on Apr 14_
+1 getting this to with .net core 2.0 referencing .net framework project.

_@CarlosOnline commented on Jun 8_
Any status on a fix?

[karelz]

We need isolated repro we can run locally to provide more details. Does anyone have one?
cc @danmosemsft

[micdenny]

@karelz I did in my repo CoreFxIssue31276

Just run it, and you will get the exception calling api/values:

[Illeris]

Issue also arises with .NET Core 2.0, referencing TeamFoundation & VisualStudio assemblies (v16 preview), when invoking "WorkItemTrackingHttpClient witClient = connection.GetClient();"
Results in exactly the same exception. Having compatibility package referenced...

[jzabroski]

I ran into this problem after the guidance in https://github.com/dotnet/standard/issues/506 told me to use .NET Core w/ Microsoft.Windows.Compatibility package instead of .NET Standard, to get past a differennt FileNotFoundException loading DLLs!

[jzabroski]

@karelz Why is this still tagged with needs more info? https://github.com/micdenny/CoreFxIssue31276 seems to be what you need?

[karelz]

The area owners didn't get to the issue yet, that's why it was not updated. Removing the label 'needs more info' now.
ping @ianhays @Anipik cc @joperezr

[joperezr]

I see what is going on here. The problem is that the compatibility package had a bug when targeting netcoreapp2.0 instead of netcoreapp2.1, but that problem has been fixed on the new compatibility package that we just released yesterday. @jzabroski and @micdenny do you guys mind updating your ASPNETCore project to use the 2.0.1 version of the Microsoft.Windows.Compatibility package? That should fix your issue.

[joperezr]

cc: @safern since he fixed the issue with the compatibility package.

[joperezr]

Closing since I have validated with @micdenny's repro that updating the version of the package fixes the issue. Do feel free to re open if people still hit this with the new package.

[safern]

Just for reference and future possible hits of this issue:

If you have a full framework library that uses one of this types, i.e System.ValueTuple and then reference this from a netcoreapp2.0 app that uses the Microsoft.Compatibility.Windows package, then we will get a runtime exception because the typeforward doesn’t exist:

Unhandled Exception: System.TypeLoadException: Could not load type 'System.ValueTuple`1' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
   at netfxApp.TestClass.UseTuple()
   at compatApp.Program.Main(String[] args) in E:\repos\compatPackTest\compatApp\Program.cs:line 10

The affected types are:

System.ArgIterator
System.ValueTuple
System.ValueTuple<T1>
System.ValueTuple<T1, T2>
System.ValueTuple<T1, T2, T3>
System.ValueTuple<T1, T2, T3, T4>
System.ValueTuple<T1, T2, T3, T4, T5>
System.ValueTuple<T1, T2, T3, T4, T5, T6>
System.ValueTuple<T1, T2, T3, T4, T5, T6, T7>
System.ValueTuple<T1, T2, T3, T4, T5, T6, T7, TRest>
System.Diagnostics.Contracts.Internal.ContractHelper
System.Reflection.Emit.EventToken
System.Reflection.Emit.FieldToken
System.Reflection.Emit.MethodToken
System.Reflection.Emit.ParameterToken
System.Reflection.Emit.PEFileKinds
System.Reflection.Emit.PropertyToken
System.Reflection.Emit.SignatureToken
System.Reflection.Emit.StringToken
System.Reflection.Emit.TypeToken
System.Runtime.CompilerServices.IAsyncStateMachine
System.Runtime.InteropServices.AssemblyRegistrationFlags
System.Runtime.InteropServices.ExporterEventKind
System.Runtime.InteropServices.IDispatchImplAttribute
System.Runtime.InteropServices.IDispatchImplType
System.Runtime.InteropServices.InAttribute
System.Runtime.InteropServices.RegistrationClassContext
System.Runtime.InteropServices.RegistrationConnectionType
System.Runtime.InteropServices.SetWin32ContextInIDispatchAttribute
System.Collections.Generic.TreeSet<T>
System.ComponentModel.InvalidEnumArgumentException
System.IO.Compression.ZLibException
System.Net.CookieVariant
System.Net.PathList

[Santhosh0505]

I am facing the same issue in .Net Core 3.0. And the Microsoft.Windows,Compatibitlity also didn't solved the issue. Please update the solution for .Net Core 3.0 or 3.1

[safern]

@Santhosh0505 which version of the Compatibility package are you using?