The maximum number of migration batches is already running

Reading Time: < 1 minute

When migrating mailboxes from Exchange Hybrid to Exchange Online (O365), you may receive the below error when attempting to migrate a new batch

The maximum number of migration batches is already running. Please remove a batch before you add another one.

The limit of the number of migration batches you can create is 100. The main purpose of why Microsoft set this limit is for performance reasons. Having more than 100 batches causes performance problems and could cause outages for other customers in the multi tenant system. You can check the limit by typing the below command within Exchange Online Powershell

Get-MigrationConfig |FL *max*

This error is common when migrating mailboxes from Exchange to O365 (Exchange Online) and users find that when they receive this error there are no other migration batches in progress.

This 100 batch number limit also includes batches which have already been completed. To get around this, remove a completed batch and start your new batch migration again. You’ll find that it works.

Please do comment below to let us know how you get on

Can’t move Exchange 2013 mailboxes back to Exchange 2007

Reading Time: < 1 minuteYou attempt to move a mailbox back from Exchange 2013 to 2007 using the GUI, but find nothing happens, the mailbox does not migrate.

I found using the Exchange Management Shell worked well when migrating a mailbox back to Exchange 2007


Outlook Anywhere users prompted for credentials when connecting to Exchange Server 2013

Reading Time: < 1 minuteYou are running Microsoft Exchange Server 2013 in a coexistence environment together with either or both Microsoft Exchange Server 2010 or Exchange Server 2007.

Users are continuously prompted for their credentials or their mailboxes remain in a disconnected state. This problem may also affect Outlook Anywhere connections to Exchange Server 2010 or Exchange Server 2007 legacy public folders or Offline Address Books.

This is a known issue and a hotfix available from Microsoft.


After installing the hotfix, reboot and test again.