'SWITCH USER' causing system freeze / crash.

[Suvendu Dey]

Problems: Choosing SWITCH USER option causing system freeze on post-login desktop session.
Not sure these are distro specific or KDE specific. I'm not pro.

 Description:
There are 3 events.
Event-1
 Choose 'SWITCH USER' from an active desktop session(https://ibb.co/V2M6gdf). Get login screen & provide password. After 5 min (in my case) you will enter & get the desktop session is frozen.

Event-2
 Step-1: Within a desktop session click Lock(or Sleep).

 Step-2: Get the Login screen (or wake up the system from suspension) but don't login there. Click 'SWITCH USER' option on that sceen(https://ibb.co/KVsTgSD). On next screen, input password in Login box. After 5 min (in my case) you will enter & get the desktop session is frozen.

Event-3

 Step-1: Within a desktop session click Sleep (additionally, one can suspend the session keeping any desktop applications e.g. Firefox running https://ibb.co/Cw92FdD).

 Step-2: Wake up the system from suspension but don't login there. Click 'SWITCH USER' option on that screen. On next screen click Sleep.

 Step-3: Wake up the system from suspension & try to login, input your password in the box. Next, login screen freezes/halts for approx 5 min (in my case) & thereafter gets into the Desktop session. The whole Desktop is frozen. Clicking on the wheel / pressing Windows key or clicking any other icons don't work. you can only hover mouse pointer.

     Access tty1 with Ctrl+Alt+F1 (if suspended with Firefox as in step-1, on tty1 at first you will get Firefox window without a title bar https://ibb.co/GvhxwCz. Login appears after quitting the Firefox). Once you input password there it freezes too.

Got 2 crash reports. @desktop https://pastebin.com/RTpGGSDX https://ibb.co/X3WV9zC
@tty1 https://pastebin.com/A4W3SvQg https://ibb.co/0m3Z0gh

 SYSTEM INFO:
Kubuntu 20.04.0
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
Kernel Version: 5.4.0-47-generic
OS Type: 64-bit
Processors: 4 × Intel® Core™ i3-7020U CPU @ 2.30GHz
Memory: 3.7 GiB of RAM

[gl.bars (gl-bars)]

Project field was incorrect.
I guess this is either plasma or sddm.

[Suvendu Dey (bijaydeyp)]

Update:https://bugs.kde.org/show_bug.cgi?id=428479