C# "Windows Runtime Component (Universal Windows)" inside C++ solution causes Windows App Certification Kit to fail "Supported API Test"

[giregk]

I'm building a React-Native-Windows project, which has a UWP C++ core.

I need to add a custom native component to this project, so I've added a C# project using "Windows Runtime Component (Universal WIndows)".

My code runs locally in debug and release mode, for both x64 and x86 platforms.

However, when I create my app package for publication to the store, the Windows App Certification Kit fails the "Supported API test" with this error:

API _XcptFilter in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API __C_specific_handler in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API _amsg_exit in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API _initterm in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API free in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API malloc in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API memcpy in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API memset in msvcrt.dll is not supported for this application type. clrcompression.dll calls this API.
API __CxxFrameHandler4 in vcruntime140_1_app.dll is not supported for this application type. TestRNWRelease.exe calls this API.
API ExecuteAssembly in uwphost.dll is not supported for this application type. UWPShim.exe calls this API.
API DllGetActivationFactory in uwphost.dll is not supported for this application type. UWPShim.exe has an export that forwards to this API.

I have found this issue which looks similar.

The solution seems to be to remove the "Microsoft.NETCore.Portable.Compatibility" dependency from the "Microsoft.NETCore.UniversalWindowsPlatform" NuGet package. But I don't know how to do that.

(Note that I am still a beginer with Visual Studio).

I have create this demo project that have the issue.
Besides, I have opened an issue on the react-native-windows project where they suggested I opened an issue here.

Any ideas how to fix this ?

[asklar]

this is because the C++ project lacks the .net native compiler nuget package reference. See this page for details and Raymond's blog post on it too.

@tommcdon I think there was some effort to make this easier/automatic in VS, is that right?