I have this problem after installing updates yesterday. Looks like like how Eugene shows in comment #10.
The attachment contains the data logged in x-0.log, seat0-greeter.log, lightdm.log, and x-1.log in the /var/log/lightdm directory during a test. I pressed CTRL-ALT-L, waited 10 seconds, clicked "Switch to greeter...", waited 10 seconds, then logged in and stopped recording. There is a DBus error, but not much else. ** Attachment added: "lightdmlogs.txt" https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1733557/+attachment/5078263/+files/lightdmlogs.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1733557 Title: Login screen showing Authentication Failure Switch to greeter... To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1733557/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
