This post describes how to fix the error 'DNString length mismatch'. Cause This error can occur when a new Outlook Web App mailbox policy is created in Microsoft Exchange.  I found this issue on Exchange 2016. The error then occurs when you try to open Outlook Web App policies tab. Trying to diagnose the issue in PowerShell by running Get-OwaMailboxPolicy also leads to the same error. Further investigation using ADSI Edit reveals the object causing the error. Resolution To resolve the issue, delete the object using ADSI Edit. The Outlook Web App policies tab now opens again.

This post describes how to fix the error "Operation terminated with error -1032 (JET_errFileAccessDenied, Cannot access file, the file is locked or in use)" This error can occur on Microsoft Exchange 2016 when you try to repair a mailbox database using eseutil. Cause The Exchange Management Console does not have the necessary privileges to access the file. Fix Open the EMC as Administrator.  eseutil should now have the privileges required to repair the database.

This post describes how to fix the error "Failed to mount database. Error: An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionDatabaseError: Unable to mount database." This error can occur on Microsoft Exchange 2016 when you try to mount a mailbox database. Cause One cause of this error is the mailbox database being in a 'dirty shutdown' state. To check the state of a mailbox database, open the Exchange Management Console and run the following (replacing the path as necessary): eseutil /mh "C:\Program Files\Microsoft\Exchange Server\V15\Mailbox\Mailbox Database 0969320567\Mailbox Database 0969320567.edb" Fix 1 To repair the database, run the following in the EMC: eseutil /p "C:\Program Files\Microsoft\Exchange Server\V15\Mailbox\Mailbox Database 0969320567\Mailbox Database 0969320567.edb" The state should now be 'clean shutdown': You should now b...

This post describes how to fix the error: Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EXCH-2K16-2/cn=Microsoft System Attendant. This error can occur on Microsoft Exchange 2016 when you try to open the add-ins section. Cause One cause of this error is if one or more mailbox databases are not mounted. Fix To resolve this issue, open the Exchange admin center, navigate to servers, then databases and check if any are dismounted.  If that is the case, select the mailbox database, press the ellipses, then press Mount. Error If the mount fails, the following post describes one way to resolve this error: Failed to mount database. Error: An Active Manager operation failed. Operation failed with message: MapiExceptionDatabaseError Video YouTube link:  Cannot open mailbox/o=first organization/ou=exchange administrative group Microsoft System Attendant