It would be useful to find out why gdm3 works for you but lightdm does not. It might be because gdm3 defaults to Wayland not Xorg, or it might be a difference in the greeter/login screen itself. To find out, please try editing /etc/gdm3/custom.conf and change:
#WaylandEnable=false to WaylandEnable=false then reboot. Does gdm3 still work now it's using Xorg? ** Tags added: radeon ** Summary changed: - Failure to pass system check and present login screen + [radeon] Failure to pass system check and present login screen ** Package changed: xorg (Ubuntu) => xorg-server (Ubuntu) ** Changed in: xorg-server (Ubuntu) Status: New => Incomplete ** Also affects: lightdm (Ubuntu) Importance: Undecided Status: New ** Changed in: lightdm (Ubuntu) Status: New => Incomplete ** Also affects: unity-greeter (Ubuntu) Importance: Undecided Status: New ** Changed in: unity-greeter (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1913855 Title: [radeon] Failure to pass system check and present login screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1913855/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs