I’ve recently been asked several times to look at why a Lync Server 2013 server’s LS Address Book Server consistently logs the event ID 21054 error whenever the address book is updated with Update-CsAddressBook cmdlet or after the maintenacne that is ran every day:
The following is a sample of the event log information details:
Users are not indexed in the database that should be.
Expected indexed user count: 0
Actual indexed user count: 216
Cause: User replication issue.
Run Update-CsAddressBook to synchronize all accounts.
As per the following Technet article:
If you execute the Debug-csAddressBookReplication -Poolfqdn <Pool FQDN for which the event was generated> cmdlet and don’t see any unindexed or abandoned objects listed then this event error can be safely ignored.
Note that the time of the writing of this post is February 2013 and Lync Server 2013 currently does not have any updates available so I assume future patches will fix this.