I had this same problem and found the issue to be with PolicyKit group settings. Common thread here seems to be -
1. Ensure /etc/hosts file is correct 2. Ensure appropriate users are added to the "polkituser" group in /etc/group -- [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 Desktop Bugs, which is a direct subscriber. -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs