Hello,
I recently migrated from Exchange 2010 to Exchange 2013. I am in the process of demoting old domain controllers (Server 2008 R2) and have shutdown the domain controllers for testing purposes. Upon shutting down, a few users are not able to sign in and sign out OWA successfully. Here are the related errors in the Event Viewer and the troubleshooting steps I have done so far.
Event Viewer Logs
1. MSExchange ADAccess (Event ID 4112)
"Process Microsoft.Exchange.EdgeSyncSvc.exe (PID=2376). AD Session operation failed on DC dc2.domain.com because this server is not suitable at the moment. DomainController value set on the session instance: dc.domain.com. ServerSettings updated: False"
2. OWA: "A server that contains information about your user account and mailbox is not available".
3. OWA: An Active Directory error 0x51 occurred when trying to check the suitability of server ‘dc2.domain.com. Error: ‘Active directory response: The LDAP server is unavailable.’
Troubleshooting
1. Set the preferred Global Catalog to new DC (Server 2012 R2).
2. Set the StaticExcludedDomainControllers to exclude the old DC.
3. Set the StaticDomainControllers to new DC for LDAP (Server 2012 R2).
I would really appreciate if anyone can share their experiences who have come across a similar issue.
Thanks,
Sathish