- The Exchange 2003 computer is upgraded from Microsoft Windows 2000 to Microsoft Windows Server 2003.
- The Microsoft Data Access Components (MDAC) file that is named Oledb32.dll is not upgraded to the correct version during the Windows Server 2003 upgrade.
- Click Start, point to All Programs, point to Administrative Tools, and then click Services.
- Stop the Microsoft Exchange Information Store service.
- Copy the Oledb32.dll file from a Windows Server 2003-based computer that was not upgraded from Windows 2000 to your Exchange computer. To do this, use one of the following methods.
Method 1Copy the file from an available Windows Server 2003-based computer that was not upgraded from Windows 2000.
266465 How to perform a parallel installation of Windows 2000 or Windows 2003Note The default location of Oledb32.dll is C:\Program Files\Common Files\System\OLE DB\Oledb32.dll.
- Install a new copy of Windows Server 2003 to a separate partition on the computer by creating a parallel installation.
- Copy the Oledb32.dll file.
- Remove the new installation, if you want.
- Copy Oledb32.dll to the same location on the Exchange computer where you are trying to resolve this issue.
- On the Exchange computer, type the following commands at the command prompt:
- cd Program Files\Common Files\System\ole db
- regsvr32 oledb32.dll
Note The Oledb32.dll file version must be 2.8.1022.0 or later to resolve the issue that is described in the "Symptoms" section.
- Start the Microsoft Exchange Information Store service.
Additionally, the following event ID message may be logged in the application event log multiple times:
The following event ID error message may be logged in the System Log in the Event Viewer multiple times:
For additional information about troubleshooting the "503 Service Unavailable" error message, click the following article number to view the article in the Microsoft Knowledge Base:
Article ID: 837285 - Last Review: Mar 29, 2017 - Revision: 3