Topic Last Modified: 2010-01-27

The Microsoft Exchange Server 2010 Management Pack for System Center Operations Manager monitors the Windows Application log on computers running Exchange 2010 and generates this alert when the events specified in the following Details table are logged.

To learn more about this alert, in Operations Manager, do one or more of the following:


Product Name


Product Version

14.0 (Exchange 2010)

Event ID


Event Source

MSExchange Availability

Alert Type


Rule Path

Microsoft Exchange Server/Exchange 2010/Client Access/Information Worker

Rule Name

The remote forest AvailabilityAddressSpace object for proxying a cross-forest request couldn't be found.


This Error event indicates that the AvailabilityAddressSpace object could not be found. The AvailabilityAddressSpace object encapsulates the information that is required to request availability data from a remote Active Directory forest. This information includes the user account and the access mechanism to request the cross-forest availability data. This event may also occur if the local Domain Name System (DNS) is not configured correctly with the information about the Active Directory forest specified in the event description. 

User Action

To resolve this error, do one or more of the following:

  • Run the this command on the server that is running Microsoft Exchange and that logged this event using the Exchange Management Shell:

    Add-AvailabilityAddressSpace -ForestName <name of the remote Active Directory Forest> -AccessMethod PublicFolder

    Note   This command is valid if the remote Active Directory forest is an Exchange Server 2003 forest.

  • Make sure that the local DNS is correctly configured to have the information about the Active Directory forest specified in the event description. For more information about how to configure and troubleshoot DNS, see Troubleshooting DNS Servers on Microsoft Windows Server TechCenter.

  • Increase the diagnostic logging level of MSExchange Availability service. To do this, follow these steps:

    Caution   Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.

    1. Start Registry Editor (regedit).

    2. Locate the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchange Availability\Diagnostics

    3. In the results pane, change the Value data of all keys (except Default) to 5.

    4. Exit Registry Editor.

  • Review related Error and Warning events in the Application log. These related events may help you find the root cause of this error.

If you cannot resolve this error using the options suggested here, contact Microsoft Product Support Services. For more information, visit the Microsoft Help and Support Web site.

For More Information

If you are not already doing so, consider running the Exchange tools created to help you analyze and troubleshoot your Exchange environment. These tools can help make sure that your configuration aligns with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. To run these tools, go to the Toolbox node of the Exchange Management Console. To learn more about these tools, see Managing Tools in the Toolbox.