In my case, I traced the issue to the keyboard-configuration package postinst script, which ends up calling 'setupcon --force --save' which in turn calls 'kbd_mode -u'
To reproduce: sudo apt install --reinstall keyboard-configuration setupcon documentation states: "--force Do not check whether we are on the console. Notice that you can be forced to hard-reboot your computer if you run setupcon with this option and the screen is controlled by a X server." It looks like the checks to avoid this behavior while a graphic environment is active don't work in the context of the installer. ** Also affects: console-setup (Ubuntu) Importance: Undecided Status: New -- 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/1508146 Title: Alt+left/right arrows switch between tty consoles (Gnome Shell vanishes), cannot disable To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/console-setup/+bug/1508146/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs