This article was previously published under Q322258
This article has been archived. It is offered "as is" and will no longer be updated.
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
The Exchange 2000 Server information store may stop responding (hang) intermittently, and then resume typical behavior. Multiple occurrences of the following warning message may be logged in the Application event log:
Event Type: Warning Event Source: MSExchangeIS Mailbox Store Event ID: 9551 Description: An error occurred while upgrading the ACL on folder [MBX:User1]/Calendar located on database "Server1\Mailbox Store 1 (server)". The Information Store was unable to convert the security for /O=ORGANIZATION/OU=SITE/CN=RECIPIENTS/CN=123456 into an NT Security Identifier. It is possible that this is caused by latency in the Active Directory Service, if so, wait until the user record is replicated to the Active Directory and attempt to access the folder (it will be upgraded in place). If the specified object does NOT get replicated to the Active Directory, use the Microsoft Exchange System Manager or the Exchange Client to update the ACL on the folder manually. The access rights in the ACE for this DN were 0x401.
If a folder (such as a calendar folder) is shared between many users, and the access control list (ACL) of the folder contains user accounts that cannot be resolved, the remote procedure call (RPC) thread pool may be used up. As each user tries to access the specific folder, the ACL on the folder must be upgraded.
While the ACL is upgraded, other users are blocked from accessing the folder until the upgrade completes. If many users simultaneously try to access the folder, the RPC thread pool may be used up. The RPC may not allow new connections to the information store until all of the attempts to convert the ACL are complete. Because the ACL contains a user account that cannot be resolved, the ACL cannot be upgraded. This problem occurs for each user account that tries to access the folder.
To resolve this problem, obtain the latest service pack for Microsoft Exchange 2000 Server. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
301378 XGEN: How to Obtain the Latest Exchange 2000 Server Service Pack
The English version of this fix has the following file attributes or later:
Component: Information store
NOTE: Because of file dependencies, this update requires Microsoft Exchange 2000 Server Service Pack 2.
Microsoft has confirmed that this is a problem in Microsoft Exchange 2000 Server. This problem was first corrected in Microsoft Exchange 2000 Server Service Pack 3.
The fix that this article describes contains a new time-out mechanism. When an ACL cannot be upgraded, the information store does not try to upgrade the ACL again for a set amount of time. By default, this period of time is 30 minutes. The result of the previous conversion is returned from cache.
You can override the default time-out value. To do so, you have to set the ACLUpdateRetryTimeout value to "0" to revert the information store to its behavior before the fix was applied.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.
To set the ACLUpdateRetryTimeout value:
Start Registry Editor (Regedt32.exe).
Locate and then click the following key in the registry: