I have a fully functioning app that I have tested locally on several phones. I now was ready to publish the app for a closed beta, which resulted in the XAP file had all kind of unsupported APIs, but when I search for them in the solution I cannot find any references.

Has somebody had experience with this?

Snippet of Unsupported APIS

This API is not supported for this application type - Api=lstrcmpW. Module=api-ms-win-core-string-obsolete-l1-1-0.dll. File=vstest.exe.  
This API is not supported for this application type - Api=GetModuleFileNameW. Module=api-ms-win-core-libraryloader-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=GetModuleHandleA. Module=api-ms-win-core-libraryloader-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=LoadLibraryExW. Module=api-ms-win-core-libraryloader-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=CreateProcessW. Module=api-ms-win-core-processthreads-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=GetStartupInfoW. Module=api-ms-win-core-processthreads-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=WaitForSingleObject. Module=api-ms-win-core-synch-l1-2-0.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=inet_pton. Module=ws2_32.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=WsAcceptChannel. Module=webservices.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=WsAlloc. Module=webservices.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=WsCloseChannel. Module=webservices.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=WsCloseListener. Module=webservices.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=WsSendMessage. Module=webservices.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=Microsoft.Phone.Shell.CycleTileData. Module=. File=Cimbalino.Phone.Toolkit.Background.dll.
This API is not supported for this application type - Api=Microsoft.Phone.Shell.FlipTileData. Module=. File=Cimbalino.Phone.Toolkit.Background.dll.
This API is not supported for this application type - Api=Sleep. Module=api-ms-win-core-synch-l1-2-0.dll. File=vstest.exe.
This API is not supported for this application type - Api=GetTickCount. Module=api-ms-win-core-sysinfo-l1-2-0.dll. File=vstest.exe.
This API is not supported for this application type - Api=RtlCaptureContext. Module=api-ms-win-core-rtlsupport-l1-2-0.dll. File=vstest.exe.
This API is not supported for this application type - Api=RtlVirtualUnwind. Module=api-ms-win-core-rtlsupport-l1-2-0.dll. File=vstest.exe.
This API is not supported for this application type - Api=SetUnhandledExceptionFilter. Module=api-ms-win-core-errorhandling-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=UnhandledExceptionFilter. Module=api-ms-win-core-errorhandling-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=TerminateProcess. Module=api-ms-win-core-processthreads-l1-1-1.dll. File=vstest.exe.
This API is not supported for this application type - Api=_fmode.    Module=msvcrt.dll. File=vstest.exe.
This API is not supported for this application type - Api=wcscat_s. Module=msvcrt.dll. File=vstest.exe.
This API is not supported for this application type - Api=wcscpy_s. Module=msvcrt.dll. File=vstest.exe.
This API is not supported for this application type - Api=wcslen. Module=msvcrt.dll. File=vstest.exe.File=vstest.executionengine.WindowsPhone.dll.File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=__dllonexit. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=_amsg_exit. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=_initterm. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=_lock. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=_onexit. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=_unlock. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=_vsnwprintf. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.
This API is not supported for this application type - Api=wcslen. Module=msvcrt.dll. File=vstest.executionengine.WindowsPhone.dll.

Any help to solving one could lead me to another hopefully?

Update I found one reference that had one issue that I have updated and that API error was removed. But the others about vstest I do not understand ?

I have read that android has something similar that they remove before compiling. Can the issue be similar on WP ?

Base on this similar thread, in order to solve the above problem, please try to remove these twoo references (Microsoft Visual Studio Windows Phone Test Core and MSTest for Managed Project), after that please rebuild your project and run the Windows Phone Store Test Kit to help prepare your apps to be accepted in the Windows Phone Store.