Sounds like this is related to VT switching. GDM is in VT1 and the login is on VT2.
While I can't reproduce the bug right now, I can kind of see how it could happen: After switching between a bunch of VTs, eventually VT1 starts showing two screens when I switch to it by Ctrl+Alt+F1: (a) For a split-second: the boot log/terminal on tty1; and then (b) The GDM login screen. It's possible your Ctrl+C is somehow reaching tty1 on (a) before the login screen redraws, which might kill GDM. Just a theory. ** Also affects: gnome-shell (Ubuntu) Importance: Undecided Status: New ** Tags added: gnome-17.10 -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/1710637 Title: Input falls through to gdm3 and terminates the session on Ctrl+C To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gdm3/+bug/1710637/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs