I think I got hit by this bug too after the kernel update to 4.15.0-24-generic. Found this on askubuntu https://askubuntu.com/questions/1051555/after-security-update-to-4-15-0-24-generic-26-ubuntu-screen-shows-log-content which solves the problem.
Switcing to another tty and then switching to lightdm solved.
I think I got hit by this bug too after the kernel update to 4.15.0-24-generic. Found this on askubuntu https:/ /askubuntu. com/questions/ 1051555/ after-security- update- to-4-15- 0-24-generic- 26-ubuntu- screen- shows-log- content which solves the problem.
Switcing to another tty and then switching to lightdm solved.