Topic Last Modified: 2007-09-20

This topic provides information to troubleshoot Event ID 9373.

When you update the offline address book (OAB) by using the Update-OfflineAddressBook cmdlet or by using a scheduled task, the following event may be logged in the Application log on a computer that is running Microsoft Exchange Server 2007:

Event Type: Error

Event Source: MSExchangeSA

Event Category: OAL Generator

Event ID: 9373

Description: OALGen detected that the file '\\<SERVER name>\ExchangeOAB\<OABGUID>\<OABGUID>-data-1.lzx' is corrupted or missing. This indicates data tampering or disk problems. Restore files in this folder from the recent backup or clean up folder content and force a full OAB generation. - Default Offline Address Book


This issue occurs when one or more OAB version 4 files are corrupted or missing. In this case, the Microsoft Outlook clients cannot download the updated files until the issue is resolved.

To resolve this issue, use one of the following methods:

  • Restore the OAB folder contents, and then update the OAB.

    If daily backups are available, restore the contents to the

    <ExchangeInstallDir>\ExchangeOAB\<OABGUID> folder, and then update the OAB. For more information, see How to Update the Offline Address Book.

    ExchangeInstallDir is a placeholder for the name of the Exchange 2007 installation directory. OABGUID is a placeholder for the name of the folder.
  • Delete the offline address book, and then update the OAB.

    If you do not have daily backups, delete the contents from the <ExchangeInstallDir>\ExchangeOAB\<OABGUID> folder, and then rebuild the OAB files by updating the OAB. For more information, see How to Update the Offline Address Book.

    Deleting the OAB and then re-creating it forces a full download for Outlook clients. This can seriously impact the network performance of your organization.

For More Information

To learn more about OABs, see Understanding Offline Address Books.

For more information about how to manage OABs, see Managing Offline Address Books.