Failed to mount database. Error: An Active Manager operation failed. Operation failed with message: MapiExceptionDatabaseError

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 be able to mount the mailbox database.

Fix 2

If the mount still fails with the same error above and the state is 'clean shutdown', move all the log files from the Transaction logs folder location then try mounting the database again.  For a default installation, these are located here C:\Program Files\Microsoft\Exchange Server\V15\Mailbox\%MailboxDatabaseName%

You can also determine the location by running the following in the Exchange Management ConsoleGet-MailboxDatabase | fl Name,EdbFilePath,LogFolderPath

Error

If the repair fails, the following post describes one way to resolve this error: Operation terminated with error -1032 (JET_errFileAccessDenied, Cannot access file, the file is locked or in use)