Ubuntu 18.04: Authentication Error on loging after lock

I'm on Ubuntu 18.04 and since today whenever I lock my system and try to log back in using my password, it shows the 'in progress' spinner for few seconds then I get the error message "Authentication error". I can successfully log in on the first start though.

I have tried to force disable Wayland by uncommenting the line #WaylandEnable=false to WaylandEnable=false in /etc/gdm3/custom.conf but it had no effect. I was originally using Xorg as well.

I've checked for any available system updates in hope of getting a fix but none are available. What can I do to investigate into and fix this error?

Update: I re-installed Ubuntu 18.04 to get rid of the issue.

Solution 1:

The gnome reconfigure command did not work for me.

What did work was changing fs.inotify.max_user_watches. I used this solution: https://askbot.fedoraproject.org/en/question/115963/gnome-authentication-error-when-logging-in-after-lock/

Solution 2:

I had the same problem. After running the following I can re-login from the lock screen.

sudo dpkg-reconfigure gnome-shell