When your Exchange database fails to mount, it affects email communication, calendar event synchronization, user logging, and more. It’s a complete disaster for the Exchange admin, which requires immediate fix. You will get the following error message when you are unable to mount the database in Exchange Server.
Exchange is unable to mount the database that you specified. Specified database: d1cdba46-6f79-46f2- ba14-3ae2fa8aad43; Error code: MapiExceptionCallFailed: Unable to mount database. (hr=0x80004005,ec=-2147467259)
Causes of the ‘unable to mount database in Exchange’ error
I have seen and fixed this issue more than a dozen times. And each time it happens due to one of the following reasons:
- Deletion of transaction logs, which were pending to be committed in database.
- Corrupt Database.
- Dirty Shutdown State due to an abrupt system shutdown.
- Database is almost full (more than 90%).
How to fix ‘Exchange database fails to mount’ issue?
You can resolve the error and mount the Exchange database again successfully using either the eseutil tool or the backup of the database.
Method 1: Replaying Log Files
If the database has uncommitted logs or is in a dirty shutdown state, we will fix it with Eseutil tool. Eseutil is a built-in command-line tool that helps to know the database state and fix consistency issues. Before we begin to repair the database, first, we need to check the database state:
- Run eseutil /mh command to verify database current state
- If the output displays the database in a dirty shutdown state, as shown below, we will fix it by replaying the missing transaction logs using eseutil.
- Fix ‘Exchange unable to mount database’ issue with soft recovery:
We will use the /r (soft recovery) switch to fix the issue without losing any data.
Run this command to replay logs:
eseutil /r /l <log files path location> /d <database path location>
- When the repair process is complete, then again run the eseutil /mh command. Doing so will let you verify that the database is in a clean shut down state or not.
- Now, you can mount the database back to exchange using the command -
Mount-MailboxDatabase -Identity '-DAGDB1.edb' However, if the database state is still dirty shutdown, we need to perform hard recovery.
Method 2: Fix Exchange unable to mount database issue with hard recovery
In cases when soft recovery method fails or the logs are infected, you should perform the hard repair on the Exchange database. Eseutil tool is even helpful in performing hard repair to test the database for any damaged pages. If there are any, then the tool will delete them.
Before using hard repair, it is important to understand that this is risky. Hard recovery will delete all the corrupt/damaged pages from the database, and this deletion is permanent. Therefore, use this command only when there are no other ways left to repair EDB files. Command to run the hard repair:
eseutil /p <EDB file path>
After this, you must defragment the database with this command:
eseutil /d <EDB file path>
And finally, run the isinteg command. Then, check if the “Exchange database fails to mount” issue is resolved.
Method 3: Resolve disk space issue
When your Exchange database is using its 100% capacity, the Information Store service will dismount the database to prevent corruption. To fix it, you must move the old log files or export the archive mailboxes using an EDB to PST converter.
Alternatively, you can increase the database size limit using the registry settings. After making the above changes, there will be white spaces left in the EDB file. To reclaim these white spaces, you must defragment the database using the eseutil /d <EDB file path> command.
Method 4: Use EDB file backup to fix ‘Exchange unable to mount database’ issue
In case eseutil fails to resolve the error, you must restore the database back to a healthy state using the last backup. Steps to do so are:
- Create a recovery database using the Exchange Management Shell (EMS).
- Restore the database from backup using the Windows Server Backup.
- Bring the restored database to ‘Clean’ state from ‘Dirty Shutdown’ state.
- Mount the new database and move the mailboxes from old EDB to new EDB file.
Note: You will lose any data saved in the database after the creation of the backup file.
Conclusion
The methods explained in this article provide practical solutions to resolve Exchange 2010 error “unable to mount database in Exchange.” However, if the methods fail to mount the database, then your EDB file is heavily corrupted. In such a situation, you must use an Exchange Recovery tool to repair the EDB file and restore the database to a healthy state. The tool deeply scans the damaged .edb file and restores every bit of data to its original state. You can use the tool, even without any log files.
Frequently Asked Questions
Q. What is the first thing to check when Exchange 2010 fails to mount a database?
A.Check the database state via eseutil /mh, verify storage availability & review Event Viewer logs to identify the cause [corruption, logs, or space-related] of the issue.
Q. Is it safe to use hard recovery (eseutil /p) for mounting errors?
A. Hard recovery should be your last option as it permanently removes corrupted data. It is only recommended when log replay or backup restoration fails.
Q. Why does Exchange show “unable to mount database” even after a restart?
A. Such an error usually happens due to dirty shutdown state, missing transaction logs or existing storage issues. Also, a restart alone cannot resolve this without taking proper recovery steps.
