The severity should be increased as it is a more serious problem than a low severity bug.

Can you post your plasma-org.kde.plasma.desktop-appletsrc? Make sure to scan it for private data first.

plasma-org.kde.plasma.desktop-appletsrc

plasma appletrc file

Thank you both. I have extracted a minimal reproducer config and posted it upstream.

Thank you! That's a really minimal config.

Thank you and that is a very valuable additional input on the upstream bug.

Should be fixed with plasma-desktop 5.23.0-2, please confirm.

Partly:

Good: plasmashell no longer core dumps.

Bad: After logging in via sddm the screen flashes the background image which user uses on both monitors, then it goes black and stays black - no desktop at all.
Full update and reboot - journalctl no longer shows any crash (obviously).

The only message of interest is not new - was there with earlier versions of plasma - added for completeness only.
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QGuiApplication(0x7fff0d857720), parent's thread is QThread(0x5593255c2d40), current thread is QThread(0x559325734b80)

Also same old bunch of errors from theme breeze-noir-dark - as above these are not new.

forgot to mention that the QObject message is from sddm-greeter - it repeats 3 times then followed by QObject::installEventFilter(): Cannot filter events for objects in a different thread.

As I said this is not new.

Any suggestions what I can do to help track this down?

More good news:
I created a new user with no plasma customizations at all and logged in no problem.

So something about the existing settings is causing the desktop to be black instead of showing background image. She also has 2 panels - 1 horizontal on bottom and one vertical on right side.
And uses a breeze-noir-dark theme.

I will investigate and see what else I can learn. So there really were 2 issues with 5.23.0 - the plasmashell crash (now fixed) and this missing desktop issue which remains.

It is still not clear to me what your issue is. Is it *just* the background image missing, or is plasmashell not loading at all?

Sorry for not being clear. The existing user after logging in has completely black screen - nothing at all is visible - no panes, no background nothing - screen is black.

Is plasmashell running at all? Please post the terminal output of the 'plasmashell --replace' command.

plasmashell was running yes - i checked using 'ps'.

I will go back to that computer and login as her and then report back on plasmashell --replace'

ok, then it seems to be an unrelated problem, probably related to multi-monitor setup.

Since there is nothing visible on screen, I switched to virtual terminal

1) ps -eaf | grep plasmashell
shows its running aloging with a bunch of /usr/lib/kf5/kioslave5 .... local:/run/user/xxx/plasmashellXXXX.N.slave-socket

2) In VT i ran plasmashell --replace as same user that logged in via sddm:
Typing what I saw in VT:

This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, waylandxcomposite-glx, xcb

Aborted (core dumped)

Could be, but it does work fine 2 monitors for a new user with default kde/plasma set up.

> In VT i ran plasmashell --replace as same user that logged in via sddm:

You need to run it on the VT where the X server is. Set DISPLAY=:0 (changing 0 as needed).

AH thanks that makes sense. I did that - it returns silently. WHen I switch back to desktop its the same - just black nothing visible.
She has been using the same config for many years - so at this point a fresh start looks to be required. I will delete all her .kde4 .local and .config and start fresh, unless there is something else you'd like me to try.

thanks for fixing the crash and for all your help.