The following error is received when migrating mailboxes:
ERROR: [4953-23-23-8004010F] Unable to open target address book container /'Contacts/'
However, when making visual confirmations on whether the migration failed, the migration was actually successful.
The thread count may be too high for the migration environment.
Decrease the migration thread count to Quest's recommended 8 -12 threads per migration console, and then remigrate the collection.