Yesterday I encountered the same problem.
In our case the problem was the binding of the OS X server with the Microsoft AD server.
I followed the following steps to resolve it:
1. Stop Profile Manager in Server.app
2. Stop Open Directory in Server.app
3. Remove AD binding from System Preferences, Users and Groups, Login Options (This took quite some time and eventually I Force quited System Preferences after noticing that the green LED from the AD binding was removed from the list)
4. Bind to AD again with system preferences
5. Started Open Directory in Server.app
6. Started Profile Manager in Server.app
If you have a similar setup you might give it a try.