Today I’ve created a second user to test something on a fresh profile.
I used KDE Plasma to switch to the second user, which worked well (I didn’t log out of my original session), but when I tried to switch back to the original user, I was redirected to SDDM to enter my password and then only a black screen appeared.
So I checked if I could switch to another TTY by pressing CTRL ALT FX and found the original TTY, where the lock screen was shown and everything worked again.
But this is just a workaround, and new users will probably not accomplish this without external help.
While scanning through open bugs in the KDE bug tracker, i found this one, that basically describes the same problem that I have: 434370 – Switch user fails
It seems like SDDM added a configuration variable ReuseSession that can be set to true to make it reuse the existing session of a user.
Apparently, when using KDE, this is more of a must-have than an optional setting, since switching users repeatedly doesn’t seem to work otherwise.
And indeed, after I set this variable to true, switching users worked flawlessly.
So I wondered why this is not the default in Manjaro.
Since this PR from 2019, this variable should default to true from upstream side, but on my system and a relatively new Manjaro VM (created ~ May 2024) this value seems to be set to false by default.
The author specifically mentions the importance of this setting for KDE Plasma.
Interestingly enough, this variable is also completely missing from the Arch Wiki: sddm.conf(5) — Arch manual pages
Is there any reason why ReuseSession should default to false when this breaks switching users?