A version mismatch was detected (Actual:6, Expected:5).

I am doing Exchange migration from 2013 to Exchange 2016, but when I click Migration from the EAC I get the following error "A version mismatch was detected (Actual:6, Expected:5)." I have migrated the migration mailbox to Exchange 2016 and checked with get-mailboxMigration* -Arbitration, I can that it was migrated to Exchange 2016 server. So far I have 3 CAS and 5 MBX on Exchange 2013 and 5 MBX+CAS on Exchange 2016, what else can be done apart from moving the migration mailbox to Exchange 2016