Retrieving the COM class factory for component with CLSID {F87D03A3-E4DB-4CA1-91D3-4B8254A90C03} failed due to the following error: 80040154 Class not registered (Exception from HRESULT: 0x80040154 (REGDB_E_CLASSNOTREG)).

I was facing this issue while I want to utilize my VB6 Code as DLL in my WPF application in .NET framework 4.0 and Visual Studio 2010.

While adding VB6.0  DLL reference studio show me the error “A reference to '.dll' could not be added. Please make sure that the file is accessible and that it is a valid assembly or COM component.”

Solution:

Another cause of facing this issue is 32 bit and 64 bit compatibility issue. There is no error while importing DLL in VS2010 installed on a 32 bit machine.