Maximum number of items that can be serialized or deserialized in an object graph is ‘2000000’

You receive the below error when moving a mailbox to another database in Exchange 2013:

The default limit for the maxItemsInObjectGraph is set to 20000000. The work around that resolved this for me is as per below:

• Open Notepad and browse to: C:\Program Files\Microsoft\Exchange Server\V15\Bin (or where you installed Exchange).
• Look for the config file (MsExchangeMailboxReplication.exe.config) and open it.

Hit ctrl + f and search for graph. You will see the below entries.

• Change the “2” to “3” in order to increase the limit.
• Restart the Microsoft Exchange Mailbox Replication service on the server you are migrating the mailbox to.
• Resume the move-request.
• Change the above back to the previous values and then restart the Microsoft Exchange Mailbox Replication service again.

I managed to complete the mailbox move after running through the above. I’m not 100% sure if this works for Exchange versions older than version 2013 though.