Same problem - can not unlock admin functions such as users/groups, date & time etc. Error - "could not authenticate. An unexpected error has occurred".
Also, strangely both Add / Remove & Synaptic Package Manager apps disappeared from my application and system menus. Cause - created a system account named "admin" with root like privelidges *** Resloution *** delete "admin" account. Seeing as I couldn't unlock the user admin tool GUI, had to remove it from the command shell. Command = deluser admin -- [users-admin] Unlock -> "Could not authenticate. An unexpected error has occurred." https://bugs.launchpad.net/bugs/194496 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs