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Ok, I can see there are loads of similar questions regarding many distro upgrades but none of the solutions or suggestions have worked for me.

Problem
I upgraded my Dell XPS laptop from Ubuntu 20.04 to 20.10 via the distro upgrade option. Since doing so, I am having problems with my desktop whereby after auto-login, I end up with a black screen with only the mouse cursor and no window decorations, taskbar etc.

Comments

  • My auto-login flashes the new standard Ubuntu background for about 5 seconds then the screen goes black.
  • The mouse pointer is visible
  • I can right click the black screen and start a terminal session, from where I can run applications from the command line
  • Any windowed application I run has no title bar, appears in the top left corner of the screen and cannot be moved nor resized
  • I created a new user and it logs in with a normal desktop in its initial state
  • I have tried dconf reset -f /
  • I have tried unity-tweak-tool --reset-unity
  • I have tried renaming my entire .config folder and rebooting
  • If I change the scale with xrandr to 0.9x0.9, I can see a little bit of the "standard" background / wallpaper along the right side of the screen and the bottom of the screen
  • If I open display settings with gnome-control-center display for my usual account there are options for multiple screens, even though I only have the laptop screen enabled. In addition, there are no scale buttons on the scale settings section
  • If I do the same for the test account I created, I get a single desktop settings screen and 100% & 200% buttons in the scale section
  • I have tried completely removing the installed NVIDIA drivers (460), with no effect

I am now out of ideas, I'm not sure which config file in my user home is driving this. I do have a backup that I took prior to the upgrade so I could roll back, but I'd rather solve the problem if possible.

Thanks for any advice. Obviously if I've missed detail or can provide further information, please advise.

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  • I had black screen right after login screen accepted my username-password. I've managed to launch desktop after switching to Desktop on Wayland in GUI.
    – StayCool
    Jun 1, 2021 at 8:20

1 Answer 1

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Ok, so in this case the fix was to replace the core.pb file in the ~/.cache/compizconfig-1 folder.

Diagnostic route was

  • rename ~/.cache folder & reboot. Problem solved
  • rename ~/.cache/compizconfig-1 folder & reboot. Problem solved
  • work through the recently changed (i.e. not old) files, renaming and rebooting.

core.pb was the culprit. The Desktop displays correctly when this file is replaced with the auto-created one. However, desktop configuration is lost (taskbar icons etc.) although this might be because of the resetting I did initially.

Posted in case this is helpful for anybody else.

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  • Where is core.pb located? What was the problem with it? It's related to recent kernel updates somehow?
    – StayCool
    Jun 1, 2021 at 8:20
  • @StayCool, core.pb is in the ~/.cache/compizconfig-1/ folder. Had to delete it and allow the system to remake it for the display to "normalize". I don't believe it's related to kernel updates, but I cannot confirm this. Can't remember which kernel I was using in 20.10 before upgrading, but it was the newest for said release at the time.
    – Bob
    Jun 2, 2021 at 9:09

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