That's likely happening when you manually set the theme at some point in the past. This could probably be handled nicer (using excessive amounts of config juggling), but given that KDM is not used by default and is going away upstream in the long run there is no point in pursuing this matter. I recommend that you transit your system to lightdm, which is the new default.
** Changed in: kde-workspace (Ubuntu) Status: New => Won't Fix -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1160771 Title: Non-existent theme configured after upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/kde-workspace/+bug/1160771/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs