[SOLVED] Plasmashell not starting at booting the system

[peerwal]

Hello everybody,

After completing all the available updates yesterday I noticed that suddenly some of the applications, such as krunner wouldn't work anymore and others could not be terminated anymore. As the shutdown app did not work either, I had to use the shutdown shell command to terminate Kubuntu. Today, when I tried to start up the system, the booting procedure stopped during displaying the kubuntu logo but did not go on into the login screen. Watching the booting procedure in the command line mode does not show any errors. after the line saying something like ...user-session... the screen is cleared. Entering the command line mode again, I can login as usual. However, if I tra to strart PlasmaShell, I get the following error:

peter@T5300: ~/kstart5 plasmashell
qt.qpa.xcb: could not connect to display
qt.qta.plugin: could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because not Qt platform plugin could be initialized. reinstalling the app may fix this problem
Available platform plugins are: wayland-org.kde.kwin.qpa, eglfs, ...
fish: 'kstart5 plasmashell' terminated by signal SIGABRT (Abbruch)

Reinstalling xcb did not fix anything.

Running any apt-get command lists a huge number of lib packages, which obvouosly are marked as 'no longer required and can be removed', which I did not do, of course, as this seems rather strange to me.

Does anybody have a suggestion, how I can get my Plasma Desktop up and running again? Any help would be highly appreciated.

Edit 1: Using startx I get a (probably gnome-shell) desktop. switching to plasmashell works but most of the destop functions are not working. Also, the display configuration in the system settings is not available. Any ideas?

Edit 2: Currently running
Kubuntu 19.10
plasma-desktop 5.18.0
Qt 5.12.4
KDE Frameworks 5.67.0
Kf5-config 1.0

[peerwal]

After the number of problems increased, I decided to do a fresh install and moved to Neon User Editon, which fixed all issues I had.

Thanks to eveybody.

[Snowhog]

Well, it might have been telling, given you did a fresh install a new, if you had done so with a freshly downloaded copy of 19.10, installing and formatting root and home. Won't know now.

[peerwal]

Wel, I am sure a fresh install of 19.10 would have worked well, too. However, I don't think it would have been telling in any way, as i had installed so many applications with a lot of customizing before that it would have been practically impossible to establish the same system configuration again. i guess, it was my messing around with the system, which lead to that 'unhealthy' status, and which I was not able to roll back again.

Thanks, anyway.

[Snowhog]

Understand, and totally agree. I don't know if you do, but if you don't, and you are willing, start keeping a log of all changes "you" introduce to your system; adding of PPAs, installing downloaded software (.deb files), etc. It is a huge help when something with you system suddenly goes awry.

[GreyGeek]

You can't go wrong with Neon User Edition, BUT, regardless of which distro release you use, keeping regular backups of your system is essential. IF you are running EXT4 then I'd recommend installing TimeShift and set it to automatic regular backups. If you run into other problems which you can't immediately resolve then restoring from the last backup before any changes that created problems would return you to a functioning system. Then, before you do any updates, PPA's for non-repository installs you can weed through them to see what caused your problems.

[peerwal]

I am using the bup backup tool of the systemsettings but I only stored the Home volume. Might be good idea to include atleast some of the root directories into the backup.