0x80040115 what does this error mean after attempting to update the batch file with the /forcerebasesuppress all errrors file is full of users that I ran it against

Q: 0x80040115 what does this error mean after attempting to update the batch file with the /forcerebasesuppress all errrors file is full of users that I ran it against
A: The most common cause for this error is invalid LegacyExchangeDNs... and the /forcerebasesuppressallupdates switch is mainly meant for resource mailboxes.