CLSIDFromProgID error resolution

You have this usually:

   CLSID InvAppClsid;

   HRESULT hRes = CLSIDFromProgID (L"Inventor.Application", &InvAppClsid);

   if (FAILED(hRes)) {

       pInvApp = nullptr ;

       return ReturnAndShowCOMError (hRes,L"ConnectToInventor, CLSIDFromProgID failed") ;

   }

Which may fail with this error:

ConnectToInventor, CLSIDFromProgID failed

Error   = 800401f3

WCode   = 0000

Meaning = Stringa dell'interfaccia non valida.

This could be that you are running the compiler as administrator and Inventor as normal user.