This looks like bug 982889, but that was fixed in 2013. Still, since this is the only remaining instance of this bug I have heard of I would recommend upgrading to Ubuntu 18.04. It is also a long term support release and if you find gnome-shell is not well suited to this machine then you can still reinstall Unity (unity-session package).
** Summary changed: - Graphics warning on restart + Xorg repeatedly fails to start [Cannot run in framebuffer mode. Please specify busIDs for all framebuffer devices] -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1849545 Title: Xorg repeatedly fails to start [Cannot run in framebuffer mode. Please specify busIDs for all framebuffer devices] To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1849545/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
