Oabgen.dll is a process belonging to the Microsoft Exchange(TM) Offline Address Book Generator. Oabgen.dll error messages may occur when the server component that generates the offline Address Book does not finish posting the changes to the public folder. Oabgen.dll errors are mostly caused by deleting or corrupting oabgen.dll file or having a registry error.

Common oabgen.dll error messages:
- "Windows could not start because the following file is missing or corrupt: C:\Program Files\Exchsrvr\bin\oabgen.dll"
- "C:\Program Files\Exchsrvr\bin\oabgen.dll missing or corrupt: Please re-install a copy of the above file."
- "Cannot find C:\Program Files\Exchsrvr\bin\oabgen.dll."
- "Cannot find Oabgen.dll."

How to install oabgen.dll file?

1. Press Start and select Run
2. Type CMD and press Enter (or if you use Windows ME, type COMMAND)
3. Type regsvr32 oabgen.dll and press Enter
4. In the end, you should receive a message saying that your file was successfully installed or uninstalled.