I am getting a MSExchangeIS Event 1002 followed by a MSExchangeIS Event 1013 which causes mailbox database to go offline. Fortunately, the DAG kicks in and the passive copy of the database activates. These two events are triggered by the OAB Generator process. I can duplicate the issue by using the cmdlet "Update-OfflineAddressBook" after re-creating the new OAB. Oddly, the two events do not happen all the time. For instance when the automatic process happens at 1:15AM (per the 8 hour OAB Generator schedule) it is successful (no errors). But then the next automatic process happens at 9:15AM, Event 1002 and Event 1013 occur causing the mailbox database to crash and passive copy mounts.
I've recreated the Offline Address Box - this did not solve the issue.
I've created a new Arbitration mailbox and set a new OAB to use the new Arbitration mailbox. This did not solve the issue.
The MSExchangeIS Event 1002 (which I think is the culprit) starts with "Unhandled exception (System.InvalidOperationException: Nullable object must have a value."
Has anyone else experienced this frustrating issue? If so, were you able to resolve it? And how?