Plasma nostart for me on two PCs

Full journal for one boot in which nothing but an attempted start of a plasma5 session via startx. No relevant errors appear in Xorg.0.log. No fails appear in dmesg. Behavior is the same when start attempt is from the DM, or whether start is via root or normal user. One PC is running on amdgpu graphics, the other on FOSS/Nvidia, with the uploaded journal from the latter. Zypper -v doesn’t indicate any omitted deps other than the fonts I refuse to let waste my disk space or update bandwidth.

On session start attempt, two popups appear sequentially reporting segfaults, the first about klauncher, the next about ksplashqml, with offers to install debug packages and a couple of buttons in lower right corner lacking any text on the developer information tab. I’m not able to discern any activity resulting from clicking on install debug symbols, even though session attempted as root, and with debug repo enabled. There seems to be no way to actually capture a KCrash Handler report, or learn which debug packages are actually needed. Report bug is grayed out. Restart application does nothing but turn gray. Reload button restores the install debug symbols button, which when clicked repeats doing nothing detectable in package management.

A while of black screen with movable mouse pointer after their dismissal the following appears in gigantic plain text:

The screen locker is broken and unlocking it is not possible anymore.
In order to unlock switch to a virtual terminal (e.g. Ctrl+Alt+F2),
log in and execute the command:

loginctl unlock-session 1

Then log out of the virtual session by pression Ctrl-D, and switch
back to the running session (Ctrl+Alt+F3).
Issuing loginctl unlock-session 1 just restores the black screen that follows popup dismissal. Killing the worthless session is apparently complicated, lots to see in ps -A:

  780 tty3     00:00:00 bash
  825 tty3     00:00:00 k5start
  826 tty3     00:00:00 startx
  850 tty3     00:00:00 xinit
  851 tty3     00:00:00 X
  856 ?        00:00:00 startplasma-x11
  861 ?        00:00:00 dbus-daemon
  878 ?        00:00:00 ksplashqml
  880 ?        00:00:00 drkonqi
  889 ?        00:00:00 dbus-daemon
  890 ?        00:00:00 plasma_waitforn
  896 ?        00:00:00 plasma_session
  902 ?        00:00:00 klauncher
  904 ?        00:00:00 drkonqi
  915 ?        00:00:00 kded5
  918 ?        00:00:00 kwin_x11
  923 ?        00:00:00 ksmserver
  970 ?        00:00:00 installdbgsymbo
  973 ?        00:00:00 kdialog
 1000 ?        00:00:00 login
 1021 ?        00:00:00 kglobalaccel5
 1023 ?        00:00:00 drkonqi
 1030 pts/0    00:00:00 bash
 1082 pts/0    00:00:00 ps

so it’s conceptually simpler to reboot to get rid of the persistent processes. The problem with that is a 90 second useless wait for session exit before systemd will proceed to actually reboot, which I can dodge with the reset button.

What may distinguish these two installations from other 15.4 installations working fine, is it’s co-located with TDE. This has never been a problem before, but maybe now in 15.4 there has appeared some clash between same-name binaries I suppose. Both PCs run Plasma from TDM just fine in 15.3, and from SDDM or LightDM in TW.

Should I take this straight to b.o.o., or does someone have suggestions other than removing TDE, installing fonts I never want to see, or installing LightDM or SDDM, both of which I strongly dislike all themes I’ve ever seen for?