was unable to log on as to the Public Folder Store “”.

Product: Exchange
Event ID: 1024
Source: MSExchangeIS
Version: 6.5.6940.0
Component: Microsoft Exchange Information Store
Message: <user name> was unable to log on as <user name> to the Public Folder Store “<name>“.

The message text in the Description section of this event is similar to: NT AUTHORITY\SYSTEM was unable to log on to the public store as NT AUTHORITY\SYSTEM. NT AUTHORITY\SYSTEM is the local system account, which is the account used in Exchange 2000 or greater to start all the Exchange services. This error means that the local system account is unable to log on to the named public folder store database on the server named in the event. The causes for this event are varied. In some cases, there is a permissions problem. In other cases, the database itself is unavailable to be logged on to, for various reasons. Here are some examples of known causes of this event:

  • The public store has been removed and the Exchange store has been started in order to create a blank public information store, but the database has not been mounted yet.
  • The “create top level public folder” permission for the Everyone group within Security tab of the Public Folders object in Exchange System Manager has been set with an explicit deny.
  • A problem during the upgrade of the Access Control Lists (ACLs) of public folders that were migrated to Exchange 2000 or greater from Exchange 5.5 causes the public store database to be unavailable for logon. This occurrence may be an associated MSExchange Event IDs 9551, 9548, or 9562 which reference specific errors upgrading the ACL on a public folder. This occurrence may or may not be associated with an MSExchangeIS Event ID 1165, which is an event that is a notification that the Exchange store does not have enough database sessions for the threads in the store process that are servicing client requests. Whenever this occurs, performance will be adversely affected.
User Action

Generally, check for related events in the application log to determine the root cause of why the local system account cannot log on to the public store. A few resolutions are as follows.

  • Use Exchange System Manager (ESM) to mount the public information store database and a new, blank public information store will be created.
  • To determine how the permissions are set, run the DSACLS utility from the command line. NOTE: DSACLS is a command-line utility that is included with Microsoft Windows 2000 Server and is installed when you install the Windows 2000 Support Tools. Remove the assigned Deny permission using DSACLS.
  • Check the application log for errors that relate to public folder expansion problems such as Event IDs 9551, 9448, and 9562. Also check for the presence of Event ID 1165. Check the Microsoft Knowledge Base for the latest information on how to resolve these errors. Make sure that the latest Exchange service pack is installed. Check for any post-service hotfixes that resolve public folder expansion symptoms.


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