How to repair COMException error 80040154?

I had the same issue in a Windows Service. All keys where in the right place in the registry. The build of the service was done for x86 and I still got the exception. I found out about CorFlags.exe

Run this on your service.exe without flags to verify if you run under 32 bit. If not run it with the flag /32BIT+ /Force (Force only for signed assemblies)

If you have UAC turned you can get the following error: corflags : error CF001 : Could not open file for writing Give the user full control on the assemblies.

To find the DLL, go to your 64-bit machine and open the registry. Find the key called HKEY_CLASSES_ROOT\CLSID\{681EF637-F129-4AE9-94BB-618937E3F6B6}\InprocServer32. This key will have the filename of the DLL as its default value.

If you solved the problem on your 64-bit machine by recompiling your project for x86, then you'll need to look in the 32-bit portion of the registry instead of in the normal place. This is HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Classes\CLSID\{681EF637-F129-4AE9-94BB-618937E3F6B6}\InprocServer32.

If the DLL is built for 32 bits then you can use it directly on your 32-bit machine. If it's built for 64 bits then you'll have to contact the vendor and get a 32-bit version from them.

When you have the DLL, register it by running c:\windows\system32\regsvr32.exe.