It appears you're still using lightdm that is not part of bionic. It was part of xenial though, so that must be a leftover from the upgrade.
** Package changed: gdm (Ubuntu) => gdm3 (Ubuntu) ** Package changed: gdm3 (Ubuntu) => lightdm (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1773268 Title: locked out of system when upgrading to bionic from xenial Status in lightdm package in Ubuntu: Incomplete Bug description: I was attempting to upgrade to bionic from xenial using do-release- upgrade but forgot to turn off screen locking. After an hour of inactivity, I ended up at the login screen but the keyboard won't allow me to enter keys in the login window and clicking the field results in a bizarre repeated "Failed to authenticate" message. See attached screenshot. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1773268/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
