Class not registered error for Instantiation of C# object via COM from VC++

Question

In a VC++ project, I am trying to create an instance (via COM) of a C# class contained within a C# project.

Facts

• Both the C# and C++ projects are compiled using .NET 4.0
• The C# .dll is being registered using regasm /codebase "CSharpProjectName.dll"", and windows command prompt reports, "Types registered successfully."
• In the c++ project, I attempt to create an instance of a class in the C# project, but I get an HRESULT of 0x80040154 - class not registered

Here is an example of my attempt to create an instance of the .NET object from the C# .dll. The concrete class I am trying to instantiate is called Employee, which for the sake of presenting my question simply, implements the IPerson interface:

    CSharpProjectName::IPersonPtr pPersonPtr;
    HRESULT hr = pPersonPtr.CreateInstance(CSharpProjectName::CLSID_Employee);

Why am I getting a "class not registered" error even though I registered the c# .dll using "regasm /codebase" and confirmed existence of the key in the registry?

Any help would greatly be appreciated. Thanks!

Answer 1

I've had that problem in the past and it was due to both processes not being 32 or 64 bit. If you are running a 32-bit OS, you can stop reading now because what I say doesn't apply.

Use regedit to try and find your ProgIds and CLSIDs in the registry. If your C++ project is 32-bit, make sure that your C# classes were registered to the 32-bit hive--HKEY_CLASSES_ROOT\Wow6432Node. If your C++ project is 64-bit, make sure that your C# classes were registered to the 64-bit hive--HKEY_CLASSES_ROOT.

If you need to register to the 64-bit hive, you may need to call the version of RegAsm.exe under c:\windows\microsoft.net\framework64...

The other possibility for things to go wrong is that you might need to run the .NET 4.0 version of regasm.exe. If you just type "regasm" in the command line, it will give you the version of regasm you are running. You might need to type the full path of .NET 4.0 version of regasm--found at c:\windows\microsoft.net\framework\v4.0.3019\regasm.exe.