How to register a 64-bit COM dll on 64-bit Windows 7?

visual-c++ com atl windows-7-x64 regsvr32
Pat Mustard picture Pat Mustard · Apr 3, 2013 · Viewed 17.2k times · Source

I'm trying to register an x64 COM server dll for use in x64 office on x64 windows 7. I have followed the instructions here but I cannot register the dll. When I attempt to I get the following error:

regsvr error message

The command I use is regsvr32 my_x64_com_server.dll

Why is this happening and is there a workaround?

Thanks in advance.

Answer

Michael Burr picture Michael Burr · Apr 3, 2013

How is the command being run? From a process or from a command line?

Make sure the command is being run from a 64-bit process (or a 64-bit cmd.exe console window). Otherwise, the %windir%\System32\regsvr32.exe command will be redirected to %windir%\SysWoW64\regsvr32.exe and a 32-bit regsrv32 will be run (which can't register 64-bit DLLs).

You could also try using %windir%\sysnative\regsvr32.exe which will redirect to the real %windir%\System32\ directory (but only from a 32-bit process, so if you use that take care to make sure no one tries to run the command from a 64-bit process).

See File System Redirector on MSDN for details.

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