Re: COM dll server registration on Windows 64 bits

"Willy Denoyette [MVP]" <>
Tue, 26 Feb 2008 18:05:30 +0100
"Olivier" <> wrote in message

Two additionals infos:

The two dlls don't have the same name but are stored at the same location

For instance:


and the tlb are stored in both dlls.


"Olivier" <> a ?crit dans le message de news:


(I apologize, if this is not the correct forum for my question, but I did
not find another one.)

Here is my question:

We have developed ? COM dll server.

This latter is compiled in 32 bits AND 64 bits (without any changes). On
Windows 64 bits, the two versions may be ran at the same time by a 32
bits and a 64 bits process client

I can't figure out if we need to change the CLSID of our COM objects for
each "bit model". I would prefer not changing them, otherwise that would
mean a lot of changes in our clients.

I tried to search these CLSID in the registry and found that they are
existing in both the 64 bits and 32 bits section (under Wow6432Node). I
know that Windows copies some registry keys from one section to the
other, but I'm not sure in which direction (maybe only when the server is
64 bits, and so on...)

I wonder also if the registration order is important (i.e. do we need to
register the 64 bits version before or after le 32 bits one?). It seems
that it may change the way registration informations are stored in the
registry. Also, sometimes, we get the "Class is not registered" error. If
we register again our server, the error disappears.

So, what is the best practice to resolve this issue?

Any help in this area will be appreciated.

Best regards,


All you need to take care of is that you register your COM server DLL's
using the right version of regsvr32.exe.
The 32-bit DLL must be registered with the 32-bit version of regsvr32
(%windir%\syswow64), while the 64-bit version must be registered with the
64-bit version (%windir%\sytem32).


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