KDE5 Plasma Fails to Start

English Install/Boot/Login
1

After a Tumbleweed upgrade, KDE5 Plasma does not start.

I login choosing the Plasma session, I get the greeter with the spinning circle, and then nothing. I can use the mouse and keyboard. This allows me to alt F2 and run applications.

But it appears the window manager is not running as the applications have no window title bars / chrome / etc. Thus I cannot move or resize windows.

This is what I have found int he /var/log/messages relating to SDDM.

https://pastebin.pl/view/0280359f

The first error I see is

2020-08-13T09:03:02.006390+02:00 linux-utl7 sddm-greeter[16304]: QObject: Cannot create children for a parent that is in a different thread.#012(Parent is QGuiApplication(0x7fffd4bc73c0), parent's thread is QThread(0x55e193e35fd0), current thread is QThread(0x55e193fa0f90)
2020-08-13T09:03:02.007116+02:00 linux-utl7 sddm-greeter[16304]: message repeated 2 times:  QObject: Cannot create children for a parent that is in a different thread.#012(Parent is QGuiApplication(0x7fffd4bc73c0), parent's thread is QThread(0x55e193e35fd0), current thread is QThread(0x55e193fa0f90)]
2020-08-13T09:03:02.007209+02:00 linux-utl7 sddm-greeter[16304]: QObject::installEventFilter(): Cannot filter events for objects in a different thread.

Are there any other logs I should be looking in?

Is the problem caused by something else?

I’ve tried searching for solutions to this but have not come up with anything consistent.

I’ve even tried using Tumbleweed-cli to switch and dup to new and older snapshots, but no joy here.

Help much appreciated.

For now, I can still use the machine by logging in with a LXQt session.

2

looking in systemctl for errors I found this.

> systemctl --failed


200~● sddm.service            loaded failed failed Simple Desktop Display Manager






> systemctl --status sddm


● sddm.service - Simple Desktop Display Manager
     Loaded: loaded (/usr/lib/systemd/system/sddm.service; disabled; vendor preset: disabled)
     Active: failed (Result: core-dump) since Thu 2020-08-13 09:02:30 CEST; 1h 44min ago
       Docs: man:sddm(1)
             man:sddm.conf(5)
    Process: 16233 ExecStartPre=/usr/bin/plymouth quit --retain-splash (code=exited, status=1/FAILURE)
    Process: 16234 ExecStart=/usr/bin/sddm (code=dumped, signal=ABRT)
   Main PID: 16234 (code=dumped, signal=ABRT)

Which confirms no sddm running.

I currently have installed

sddm 0.18.1-3.1-x86_64 from vendor openSUSE

3

Creating a brand new user and logging in with KDE5 Plasma, has the same results, sddm crashes. Which means it is not a profile configuration or cache specific issue.