Public bug reported: I'm reporting this against xorg, because of where the problem occurs, as indicated below, I can't tell if the problem is with xorg, lightdm or light-locker. The system is a Dell Optiplex 745 single-booting to Xubuntu 20.04 up-to-date as of today.
I replaced one of 2 monitors, the one rotated to portrait orientation, with a higher resolution monitor. Started the system, logged in as another user and changed the desktop background however, when I then logged out and restarted the system, it behaved normally until it displayed the usual /dev/sda1: clean, xxxxx/xxxxx files, xxxx/xxxxx blocks on both monitors. The prompt remained for a few seconds, slowly blinked off and on 6 times, and then remained with no further activity. The system works fine if I boot from a Xubuntu 18.04 DVD (I didn't have a 20.04 DVD, and this is the only machine with a burner). On another machine, I determined that the system was booting, because the machine was visible on the network, and its shared folders were accessible. I could get to a login prompt and log on using Alt+F1 to F6. Alt-F7 returned me to the file system check prompt. I was able to start xorg after logging on with startx, and changing all settings for the new monitor, everything worked normally until logging out, which of course returned me to the command line where I had given the command startx. If I log out requesting a restart, the system reboots, but still stops at the same place every time. That behavior hadn't changed the next day. I can use the machine, but only by selecting a terminal, logging as myself or the other user and giving the startx command. I have been unable to find anything on the Internet that corrects the problem. Since the problem first started, two crashes have occurred and I allowed them to be reported; however, they were light-locker crashes. I reinstalled lightdm and light-locker, but that made no difference. I installed gdm3, which works fine, but switching back to lightdm with: sudo dpkg-reconfigure gdm3 sudo dpkg --configure lightdm resulted in: dpkg: error processing package lightdm (--configure): package lightdm is already installed and configured Errors were encountered while processing: lightdm So I can't really be sure if the problem is with xorg, lightdm or light- locker, but since there are no error messages and everything else works fine, it's clearly a bug, if a strange one. I do not relish the idea of having to reinstall Xubuntu; so for the time being, I'll use gdm3, though I prefer lightdm's ability to properly display backdrops and use the two monitors properly extended (with gdm3, the mouse moves down the left portrait monitor before moving onto the right monitor where gdm3 sees fit to put the logon dialog). The next thing I'll try is autoremoving lightdm rebooting a few times and then reinstalling it... Because of the absence of error messages and information even suggesting why X isn't starting, I have no idea what other information about my system might be useful to you, but if you need something additional, I'll try to provide it. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: xorg 1:7.7+19ubuntu14 ProcVersionSignature: Ubuntu 5.4.0-65.73-generic 5.4.78 Uname: Linux 5.4.0-65-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.14 Architecture: amd64 BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log' CasperMD5CheckResult: skip CompositorRunning: None CurrentDesktop: XFCE Date: Fri Jan 29 22:12:37 2021 DistUpgraded: 2020-10-20 06:56:14,405 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py' DistroCodename: focal DistroVariant: ubuntu DkmsStatus: virtualbox, 6.1.16, 5.4.0-62-generic, x86_64: installed virtualbox, 6.1.16, 5.4.0-65-generic, x86_64: installed ExtraDebuggingInterest: Yes GraphicsCard: Advanced Micro Devices, Inc. [AMD/ATI] RV620 LE [Radeon HD 3450] [1002:95c5] (prog-if 00 [VGA controller]) Subsystem: Dell OptiPlex 980 [1028:0342] InstallationDate: Installed on 2019-11-29 (427 days ago) InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426) MachineType: Dell Inc. OptiPlex 780 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-65-generic root=UUID=68c4f426-dc84-48e8-be0f-cd1a5acfb729 ro quiet splash vt.handoff=7 SourcePackage: xorg UpgradeStatus: Upgraded to focal on 2020-10-20 (101 days ago) dmi.bios.date: 08/06/2013 dmi.bios.vendor: Dell Inc. dmi.bios.version: A15 dmi.board.name: 0C27VV dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 6 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA15:bd08/06/2013:svnDellInc.:pnOptiPlex780:pvr:rvnDellInc.:rn0C27VV:rvrA00:cvnDellInc.:ct6:cvr: dmi.product.name: OptiPlex 780 dmi.sys.vendor: Dell Inc. version.compiz: compiz N/A version.libdrm2: libdrm2 2.4.102-1ubuntu1~20.04.1 version.libgl1-mesa-dri: libgl1-mesa-dri 20.2.6-0ubuntu0.20.04.1 version.libgl1-mesa-glx: libgl1-mesa-glx 20.2.6-0ubuntu0.20.04.1 version.xserver-xorg-core: xserver-xorg-core 2:1.20.9-2ubuntu1.2~20.04.1 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1 ** Affects: xorg (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug focal ubuntu -- 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: Failure to pass system check and present login screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1913855/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs