MissingMethodException

[holmes000]

Hello, I'm trying to use WPF in a C# dll with exported functions. To use WPF functions, afaik calling thread must be STA, so I have two solutions:

1. Use CoInitializeEx in C++ before calling exported C# function.
2. Create STA thread in C# and handle WPF related stuff there.

Either way I have to use System.Threading to create new STA thread or check current thread apartment state (to be sure no one called exported function from non-STA thread).
Here's simplified code of what I'm trying to do (using solution 1):

But when calling this function from C++, I'm getting MissingMethodException:

There are no errors/warnings on C# compilation.
What can be causing this exception?

The question is related to:

• DllExport -version: 1.7.4.29858+c1cc52f
• Copy-paste from Data tab:

Installed: True; 1.7.4+c1cc52f; invoked: 1.7.4
Project type: Cs
Storage: ProjectFiles
Compiler.Platform: Auto
Compiler.ordinalsBase: 1
Compiler.rSysObj: False
Compiler.ourILAsm: False
Compiler.customILAsm: 
Compiler.genExpLib: False
Compiler.peCheck: PeIl
Compiler.patches: None
PreProc.Type: ILMerge, IgnoreErr
PreProc.Cmd: 
PostProc.Type: None
PostProc.ProcEnv: $(SolutionPath);$(MSBuildThisFileFullPath)
PostProc.Cmd: 
SignAssembly: 
Identifier: F7BEC497-731F-43D8-960C-37B1189234FC
Instance: C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Current\Bin\amd64\MSBuild.exe
Project path: C:\Users\nouser\source\repos\interops\opsinterface\opsinterface.csproj
Action: Configure
PlatformTarget: 
TargetFramework: netcoreapp3.1
TargetFrameworks: 
TargetFrameworkVersion: 
RootNamespace: 
AssemblyName: 
MgrArgs: 
MetaLib: tools\raw\lib\net20\DllExport.dll
MetaCor: tools\raw\lib\netstd\DllExport.dll
Proxy: 
StoragePath: .net.dllexport.targets
ddNS: opsinterface
ddNS max buffer: 500
UseCecil: True
intermediateFiles: False
timeout: 30000
Options: None
RootPath: C:\Users\nouser\source\repos\interops\
PkgPath: C:\Users\nouser\source\repos\interops\packages\\DllExport.1.7.4\
SlnFile: 
SlnDir: C:\Users\nouser\source\repos\interops\
DxpTarget: tools\net.r_eg.DllExport.targets
MsgGuiLevel: -1
LockIfError: 

[3F]

I think this is #132. But you can also check #155. Thanks!

[holmes000]

So using .NET Standard 2.0 could solve this issue?

[holmes000]

Moving to .NET Standard 2.0 helped to solve this issue. Now everything works as I expected using both solutions.
However, I had to move to .NET Framework, because .NET Core supports WPF only from 3.0 (which is .NET Standard 2.1 which produces described issue).

Thanks for help and your contribution to this project!

[3F]

@holmes000 For 1.7.x the most stable is .NET Standard 2.0 and .NET Core 2.2. Others above are case-specific.

But this can be improved later. Follow the news.
Thanks for using,