Microsoft KB Archive/174172

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XADM: Error Message: An Unknown, Unexpected Error Has Occurred

Article ID: 174172

Article Last Modified on 10/28/2006


  • Microsoft Exchange Server 5.0 Standard Edition
  • Microsoft Exchange Server 5.5 Standard Edition

This article was previously published under Q174172


When you start the Exchange Administrator program, the following error message may appear:

An unknown, unexpected error has occurred.
MAPI or an unspecified service provider
ID no. 0000000-0000-00000000


This may be due to an incorrect version of Riched32.dll or Mapi32.dll in the system32 directory on this computer. This problem may occur if the system has been downgraded to a previous version of Exchange. Setup will not overwrite newer files, and because the newer DLL file is not backward compatible, this error will occur.


To resolve this problem, do the following:

  1. Rename Riched32.dll and Mapi32.dll in the winnt\system32 directory.
  2. Run Exchange Server Setup and choose Reinstall. If any Exchange service packs were applied, they need to be reinstalled.

Keywords: kbusage KB174172