Not an executable when running Regsvr32.exe on 64-Bit Windows

 

When you attempt to run Regsvr32.exe to register a 32-bit dynamic-link library (DLL) on a 64-bit version of Windows, you receive the following error message:
Filename.dll is not an executable file and no registration helper is registered for this file type.

This behaviour occurs because the Regsvr32.exe file in the System32 folder is a 64-bit version. When you run Regsvr32 to register a DLL, you are using the 64-bit version by default.

To resolve this issue, run Regsvr32.exe from the %SystemRoot%\Syswow64 folder. For example, type the following commands to register the DLL:

cd \windows\syswow64
regsvr32 c:\filename.dll