I think I've solved it. I removed gdm3 and lightdm apt purge gdm3 apt purge lightdm
then reinstalled gdm3 and ubuntu desktop. apt install gdm3 ubuntu-desktop It now seems to be working as expected. It appears to me screen blanking may not work with lightdm, but I'm not sure perhaps it was something else held over form 18.04. Just switching from lightdm to gdm3 caused a "Low Graphics Mode" error, removing and reinstalling gdme3 solved that. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1905982 Title: Screen not Blanking after upgrade to 20.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1905982/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs