I’ve recently been moving many clients to Office 365, and ran into a small problem for a particular client when performing a migration from an existing in-house Exchange server. Many users in the domain were failing migration, and gave the following error:
Failed to update one of the recipient properties. Couldn’t find a user or contact with identity “/o=Company/ou=First Administrative Group/cn=Recipients/cn=user”
This error in my case was caused by the manager field in the Active Directory being populated with the “user” common name (CN) quoted above. Removing/clearing the manager field fixed the issue and once the migration batch was re-run the users got migrated just fine. You can find the “Manager” field for a user in the “Organization” tab in Active Directory.
Thanks to Marcel at the MS Community forums for posting the fix!