stalledduetotarget_mdbavailability Office 365 migration error

by Milan Stanojevic
Milan Stanojevic
Milan Stanojevic
Windows & Software Expert
Milan has been enthusiastic about technology ever since his childhood days, and this led him to take interest in all PC-related technologies. He's a PC enthusiast and he... read more
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how to fix stalledduetotarget_mdbavailability Office 365 migration error
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The stalledDueToTarget_MdbAvailability status you’re seeing is such a buzz kill. Maybe you were moving mailboxes from Exchange 2010 to Exchange 2016 using migration batch in EAC and finally noticed that some mailboxes take a long time to complete migration.

Others describe getting the same stalledDueToTarget_MdbAvailability migration error message when transferring a mailbox from Exchange 2013 to Exchange Online and examples may continue.

This is often an indicative of a target database issue. That’s where you’re moving the mailbox to, and it should be an active copy.

There are instances when no unique solution can be given. In this short guide, we’ll though make sure there’s something you can do to fix this.

How can I fix stalledduetotarget_mdbavailability error?

1. Move a single mailbox by using the New-MoveRequest


For troubleshooting this migration error, you should first try to move a single mailbox by using the New-MoveRequest. Don’t hesitate to specify the target mailbox as a new one.

This should work if the issue was indeed caused by a database copy.

2. Increase the number of simultaneous mailbox moves

  1. Open Explorer on the Exchange server.
  2. Go to C:Program FilesMicrosoftExchange ServerV14Bin. This is the default path; the path on your server might be different.
  3. Make a backup copy of the file MSExchangeMailboxReplication.exe.config.
  4. Open MSExchangeMailboxReplication.exe.config.
  5. Then, find the following part in the file:
    MaxRetries = “60”
    MaxCleanupRetries = “5”
    MaxStallRetryPeriod = “00:15:00”
    RetryDelay = “00:00:30”
    MaxMoveHistoryLength = “2”
    MaxActiveMovesPerSourceMDB = “5”
    MaxActiveMovesPerTargetMDB = “2”
    MaxActiveMovesPerSourceServer = “50”
    MaxActiveMovesPerTargetServer = “5”
    MaxTotalMovesPerMRS = “100”
    FullScanMoveJobsPollingPeriod = “00:10:00”
    MinimumTimeBeforePickingJobsFromSameDatabase = “00:00:04”
    ServerCountsNotOlderThan = “00:10:00”
    MRSAbandonedMoveJobDetectionTime = “01:00:00”
    BackoffIntervalForProxyConnectionLimitReached = “00:30:00”
    DataGuaranteeCheckPeriod = “00:00:10”
    DataGuaranteeTimeout = “00:30:00”
    DataGuaranteeLogRollDelay = “00:01:00”
    EnableDataGuaranteeCheck = “true”
    DisableMrsProxyCompression = “false”
    DisableMrsProxyBuffering = “false”
    MinBatchSize = “100”
    MinBatchSizeKB = “256” />
  6. Change these parameters to fix the error:
    MaxActiveMovesPerSourceMDB = “5
    MaxActiveMovesPerTargetMDB = “2
    MaxActiveMovesPerSourceServer = “50
    MaxActiveMovesPerTargetServer = “5
    MaxTotalMovesPerMRS = “100
  7. Use the following command: Restart-Service MSExchangeMailboxReplication to restart the Mailbox Replication service and keep the changes.

If you see the migration error after successfully moving a few mailboxes, then it may be caused by a limit for the number of simultaneous mailbox moves.

Increase it by modifying some parameters’ value in MSExchangeMailboxReplication.exe.config file.

3. Microsoft Office 365 Support

Contact Office Support

In case the issue still persists even after performing the steps listed above, then create a ticket within Microsoft Office 365 Support. Other users did the same and the support team suspected it could be an issue with Throttling.

They have decreased the throttling thus solved the problem.

You can always use a third-party email client program that supports Exchange to access and manage your mailboxes. The software will allow you to connect to your Exchange account with your email address and password. In case it won’t be able to detect your server details automatically, you will have to enter them as well in order to use the email client program.

Get Mailbird

Make sure that this stalledduetotarget_mdbavailability Office 365 migration error isn’t here to stay! Just apply the above tips one by one. For those whom we’ve helped, spread the word as others face the same issue too.


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