COM .NET DLL not registering in the GAC (REGDB_E_CLASSNOTREG)

Question

I built a .net COM dll (debug x64) on one machine. I have it all setup and working there (I can see it in C:\\Windows\\Micorosft.NET\\assembly and OLEVIEWER).

I took the dll to another machine (along with it's .h and .c file generated from MIDL). I register the dll into the GAC by following these steps http://codeingaddiction.blogspot.com/2011/06/how-to-add-strong-name-to-existing-dll_16.html - create key pair, generate MISL, rebuild assembly from MISL with the key, and then adding it to the GAC. It seems to be in the GAC, and I can try searching for it with gacutil /l MyDllName. However, in my client application, when I link against it, at run time when invoking CoCreateInstance I get REGDB_E_CLASSNOTREG (HRESULT). I can't see the dll in C:\\Windows\\Microsoft.NET/Assembly nor in OLEVIEW.

Have I missed out any steps, or done something wrong?

Thanks

Answer 1

The reason you are getting the error REGDB_E_CLASSNOTREG is because your .net COM DLL is not registered. Any .net assembly needs to be registered for it to be exposed as a com class to the clients. We need to use regasm.exe to register the .net assembly.