The terminal window in which you ran ubuntu-bug will tell you the bug ID. If you've lost that then try looking at https://errors.ubuntu.com/user/ID where ID is the contents of /var/lib/whoopsie/whoopsie-id
That all said, your previous_boot.log mentions: aug 15 23:38:55 poema whoopsie[5963]: [23:38:55] Parsing /var/crash/_usr_bin_gnome-shell.1000.crash. aug 15 23:38:55 poema whoopsie[5963]: [23:38:55] Uploading /var/crash/_usr_bin_gnome-shell.1000.crash. aug 15 23:38:56 poema whoopsie[5963]: [23:38:56] Sent; server replied with: No error aug 15 23:38:56 poema whoopsie[5963]: [23:38:56] Response code: 200 aug 15 23:38:56 poema whoopsie[5963]: [23:38:56] Reported OOPS ID 9c43cbd2-a0d3-11e8-a8b5-fa163e192766 which I have now tracked down on our servers... It is bug 1787512. Next, please: 1. Delete all the files in /var/crash. 2. Wait for the problem to happen again and report the gnome-shell crash again (hopefully). 3. Tell us if you get directed to that same bug repeatedly, or if you can't tell then attach another 'journalctl -b-1' log. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gdm3 in Ubuntu. https://bugs.launchpad.net/bugs/1787277 Title: gdm3 freezes then locks out user after upgrade from 16.04 to 18.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1787277/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs