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I have a System76 Thelio with an NVidia RTX 3060 video card. I was running Ubuntu 20.04 with no issues.

I upgraded to 22.04, and now get an error message "Could not switch the monitor configuration" popup before logging in. If I dismiss the popup, everything seems to work as expected.

In trying to track this down, I noticed that xrandr -q displays a mysterious 3rd output. This also shows up in the Display section of System Settings.

I do have a third output on the video card, but nothing is plugged in, and I did not have this problem with 20.04.

Here is what is displayed by xrandr --verbose (just the ghost output, which shows up at the end):

None-1-1 connected (normal left inverted right x axis y axis)
    Identifier: 0x204
    Timestamp:  14563613
    Subpixel:   unknown
    Clones:    
    CRTCs:      4
    Transform:  1.000000 0.000000 0.000000
                0.000000 1.000000 0.000000
                0.000000 0.000000 1.000000
               filter: 
    PRIME Synchronization: 1 
        supported: 0, 1
    link-status: Good 
        supported: Good, Bad
    CONNECTOR_ID: 35 
        supported: 35
    non-desktop: 0 
        range: (0, 1)
  1920x1200 (0x206) 138.240MHz +preferred
        h: width  1920 start 1920 end 1920 total 1920 skew    0 clock  72.00KHz
        v: height 1200 start 1200 end 1200 total 1200           clock  60.00Hz

I have tried xrandr --auto, and xrandr --output None-1-1 --off in an effort to "disconnect" this output.

The nvidia-settings program only displays the two outputs that are connected (HDMI-0 and DP-0).

I don't have an xorg.conf file. ~/.config/monitors.xml looked "reasonable" to me, but I haven't tried removing it yet.

Here is xrandr --current:

Screen 0: minimum 8 x 8, current 5760 x 2160, maximum 32767 x 32767
HDMI-0 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 697mm x 392mm
   3840x2160     60.00*+  59.94    50.00    30.00    29.97    25.00    23.98  
   2560x1440     59.95  
   2048x1280     60.00  
   2048x1080     24.00  
   1920x1080     60.00    59.94    50.00    25.00    23.98  
   1600x1200     60.00  
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1280x720      59.94    50.00  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    59.94    59.93  
DP-0 connected primary 1920x1200+3840+389 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200     59.95*+  59.88  
   1920x1080     60.00    59.94    50.00    23.98  
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1280x720      60.00    59.94    50.00  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    59.94    59.93  
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 disconnected (normal left inverted right x axis y axis)
None-1-1 connected (normal left inverted right x axis y axis)
   1920x1200     60.00 +

I would like to "disconnect" this output so that I don't get the error.

Any ideas?

Andy Van Pelt
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  • This may be related to using Unity. When I clean installed Ubuntu 22.04, I did not run into this. When I then tried to add Unity, I hit this error. – Andy Van Pelt Apr 09 '24 at 23:52
  • It is not related to unity, same for cinnamon. For me it happened after reinstall to next minor version AND updating lenovo firmware. My bets are on latter. – Martin Mucha Jun 04 '24 at 19:23

2 Answers2

7

Just ran into this recently (I had wrongly assumed this was caused by trying out potentially-beta nvidia drivers with the lowlatency kernel, but it's happening on the main branch series too now..) and seems to be due to a change around the simpledrm driver, making it either always enabled by default or such that just nvidia_drm.modeset=1 is no longer sufficient to disable it (presumably set by some nvidia package)

From https://bbs.archlinux.org/viewtopic.php?id=288009

Reboot, adding this to your kernel parameters

initcall_blacklist=simpledrm_platform_driver_init

You can test it out by booting while holding [shift] to get to the grub menu, e to edit for this boot, then adding it to the linux line's content

To make the change permanent

echo 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT initcall_blacklist=simpledrm_platform_driver_init"' | sudo tee /etc/default/grub.d/99_disable_simpledrm.cfg
sudo update-grub

To undo the change, just remove the file and run sudo update-grub
(presumably a future version of some nvidia package will package this change or better nuisance fix for us)

sudo rm /etc/default/grub.d/99_disable_simpledrm.cfg
sudo update-grub

See also Answer to What is the difference between GRUB_CMDLINE_LINUX and GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub

Finally, the file in grub.d must at least end in .cfg to be included in the config rebuild (otherwise it'll be silently skipped)

ti7
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  • Thanks, indeed this has nothing to do with Unity, and everything to do with NVidia. I see this phantom display shows up in my Ubuntu 24.04 install, but only on the machine s with an NVidia GPU. I haven't had a chance to try your solution, as I switched away from Unity for other reasons. Thanks again! – Andy Van Pelt May 16 '24 at 20:36
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    I went with permanent solution right up, and it hanged the boot process for me. Im pretty positive I didn't have any typo in it, and removal of it fixed it again. So if anyone tests it, please be cautious and do really test it first, to avoid using live usb to fix this ;) – Martin Mucha Jun 03 '24 at 13:21
  • alas! did you find another solution? – ti7 Jun 03 '24 at 21:28
  • I tried once again, this time with just editing boot options on "Ubuntu Cinnamon 24.04 LTS Noble Numbat” and adding this option causes laptop to not boot. It will halt almost immediately in boot process, even decrypting luks won't be reached. ~ No, I'm not aware of any other solution, ghost monitor is present and even other monitors behaves incorrectly (while everything was fine in previous version – Martin Mucha Jun 04 '24 at 07:23
  • smells like nvidia optimus "bumblebee" to me.. so you may find you can boot if you force always dedicated in the BIOS in such a case, but at a tremendous battery cost .. I think this is the upstream bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2060268 with some solutions, but realistically, downgrading the driver and/or downgrading to 22.04 (or 23.xx) is probably best – ti7 Jun 04 '24 at 11:50
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    here I was recommended solution, which seems to work without downgrade/reinstall. https://askubuntu.com/questions/1516532/how-do-disable-get-rid-of-prime-display – Martin Mucha Jun 04 '24 at 19:33
  • curious/excellent - that appears a little differently to mine, which iirc was always a very small resolution like 640x480 – ti7 Jun 04 '24 at 20:19
  • I followed the following and it works. Thank you @ti7. echo 'GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT initcall_blacklist=simpledrm_platform_driver_init"' | sudo tee /etc/default/grub.d/99_disable_simpledrm.cfg sudo update-grub – passion Aug 17 '24 at 13:07
  • Somehow, on my last reboot, this method failed, so again I had that second screen. I was glad to have found this other live command line method to avoid re-rebooting (my server takes over 2 minutes to reboot, I just don't like to do that). – Alexis Wilke Aug 30 '25 at 16:02
3

I found a solution on Reddit:

Modify the Xorg configuration (e.g. using a drop-in configuration file at /etc/X11/xorg.conf.d/10-monitor.conf) like so:

Section "Monitor"
    Identifier "None-1-1"
    Option "Ignore" "true" 
EndSection

If the file doesn't exist already, you can create an empty 10-monitor.conf file and add the above. Then logout and login and voila.

MrUser
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    This works for me, and it is much easier than the grub method – Chen Deng-Ta Sep 01 '24 at 01:39
  • Thanks. This solution worked for me on a desktop computer running Ubuntu 22.04.4 LTS with an nvidia graphics card, with a single monitor connected via DisplayPort. – ingo-m Sep 05 '24 at 10:50
  • Thank you very much! This works for me on a fresh Ubuntu 24.04 install on a Meteor Lake ThinkPad p1 gen 7 running on X.org. One further issue I found this to cause is that when I undock the laptop from its desktop monitor, the mouse pointer appears to have moved to this "Unknown Display" so I have to move it around (harder than it sounds: you have to figure out the right direction) for it to reappear on the laptop's display. – sxc731 Dec 22 '24 at 09:52