Profile Manager: Enroll gives a error 500
Bit late to the party, but it seems to be resolved through opening Server, turning Off open directory, waiting a few seconds, then turning it back On. Repeat if necessary.

This has happened twice in the past month, both times were resolved by doing this. I'm now searching as to why this occurs, and if it happens again I'll test reinstalling the Server App.

Hopefully this helps someone.