Failed to mount database in Exchange Server

You want to mount a mailbox database in Exchange Server. However, instead of the mailbox database being mounted, the Exchange Server shows the error: Failed to mount database. In this article, you will learn why this happens and the solution for unable to mount database in Exchange Server.

Unable to mount database

So we have 5 mailbox databases mounted in Exchange Server. We like to mount the 6th mailbox database with the name DB06.

The below error appears.

error
Failed to mount database "DB06". Error: An Active Manager 
operation failed. Error: The database action failed. Error: 
Operation failed with message: 
MapiExceptionTooManyMountedDatabases: Unable to mount 
database. (hr=0x8004060e, ec=-2147219954) Diagnostic 
context: Lid: 65256 Lid: 10722 StoreEc: 0x8004060E Lid: 1494 
---- Remote Context Beg ---- Lid: 59596 dwParam: 0x6589FEE 
Msg: SM01 Lid: 59596 dwParam: 0x6589FEE Msg: SM02 Lid: 
59596 dwParam: 0x6589FEE Msg: SM03 Lid: 59596 dwParam: 
0x6589FEE Msg: SM04 Lid: 59596 dwParam: 0x6589FFD Msg: 
SM05 Lid: 39576 StoreEc: 0x977 Lid: 35200 dwParam: 0x3DF4 
Lid: 58864 StoreEc: 0x8004060E Lid: 43248 StoreEc: 
0x8004060E Lid: 35388 StoreEc: 0x8004060E Lid: 59596 
dwParam: 0x6589FFD Msg: SM08 Lid: 59596 dwParam: 
0x6589FFD Msg: SM12 Lid: 35200 dwParam: 0x3DF4 Lid: 1750 
---- Remote Context End ---- Lid: 1047 StoreEc: 0x8004060E 
[Database: DB06, Server: EX01-2019.exoip.local] 

Let’s mount the mailbox database with PowerShell.

[PS] C:\>Mount-Database "DB06" -Confirm:$False

After running the above command, this is how the error looks.

Failed to mount database "DB06". Error: An Active Manager operation failed. Error: The database action failed. Error:
Operation failed with message: MapiExceptionTooManyMountedDatabases: Unable to mount database. (hr=0x8004060e,
ec=-2147219954)
Diagnostic context:
    Lid: 65256
    Lid: 10722   StoreEc: 0x8004060E
    Lid: 1494    ---- Remote Context Beg ----
    Lid: 59596   dwParam: 0x6582D8D  Msg: SM01
    Lid: 59596   dwParam: 0x6582D8D  Msg: SM02
    Lid: 59596   dwParam: 0x6582D8D  Msg: SM03
    Lid: 59596   dwParam: 0x6582D8D  Msg: SM04
    Lid: 59596   dwParam: 0x6582D9C  Msg: SM05
    Lid: 39576   StoreEc: 0x977
    Lid: 35200   dwParam: 0x3DF4
    Lid: 58864   StoreEc: 0x8004060E
    Lid: 43248   StoreEc: 0x8004060E
    Lid: 35388   StoreEc: 0x8004060E
    Lid: 59596   dwParam: 0x6582D9C  Msg: SM08
    Lid: 59596   dwParam: 0x6582D9C  Msg: SM12
    Lid: 35200   dwParam: 0x3DF4
    Lid: 1750    ---- Remote Context End ----
    Lid: 1047    StoreEc: 0x8004060E [Database: DB06, Server: EX01-2019.exoip.local]
    + CategoryInfo          : InvalidOperation: (DB06:ADObjectId) [Mount-Database], InvalidOperationException
    + FullyQualifiedErrorId : [Server=EX01-2019,RequestId=a5091c2f-5fd8-4e3b-906a-88c0396ef1c8,TimeStamp=5/7/2023 3:59
   :51 PM] [FailureCategory=Cmdlet-InvalidOperationException] 366D03B8,Microsoft.Exchange.Management.SystemConfigurat
  ionTasks.MountDatabase
    + PSComputerName        : ex01-2019.exoip.local

Why are we getting this error, and what is the solution for failed to mount database in Exchange Server?

Exchange Server editions

Microsoft Exchange Server has two editions:

1. Exchange Server Standard (maximum of 5 mounted mailbox databases)
2. Exchange Server Enterprise (maximum of 100 mounted mailboxes databases)

If you do not enter a product license key, it will run as a Trial edition. The Trial Edition has the same features as Exchange Server Standard Edition.

Read more: Exchange Server Edition comparison »

Note: You can only add mount 5 mailbox databases if you have a Standard Trial Edition or Standard Edition. If you mount the 6th database, it will show the failed to mount database error.

This is the Standard Trial Edition:

This is the Standard Edition (licensed):

Solution for failed to mount database

The next time you have a migration planned or a new Exchange Server configuration. Ensure you know how many mailbox databases you need to mount in Exchange Server. You can use a Standard Trial Edition or Standard Edition with less than five mailbox databases.

Do you need to mount more than 5 mailbox databases in Exchange Server? The only working method is to have the Exchange Server Enterprise license key entered. If not, you will get an error, and it’s impossible to proceed further than the maximum of 5 mailbox databases.

Let’s enter the Enterprise product key in Exchange Server.

The 6th mailbox database is successfully mounted.

Keep reading: Configure mount points for Exchange Server »

Conclusion

You learned why you are unable to mount the mailbox database. The solution to this problem is to enter an Exchange Server Enterprise Edition product key. After that, you can mount the mailbox database successfully.

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