SUMMARY STEPS TO REPRODUCE 1. Setup autologin for a user 2. Change the username or entry in /etc/sddm.conf 3. Restart the system OBSERVED RESULT SDDM will crash when the service is started EXPECTED RESULT SDDM falls back to the login screen SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: KDE Neon User Edition, 18.04 (available in About System) KDE Plasma Version: 5.18.3 KDE Frameworks Version: 5.68.0 Qt Version: 5.14.1 ADDITIONAL INFORMATION This bug was reported on behalf of a user. Unfortunately I don't have access to a functional KDE Neon machine directly. I also apologize if I reported this to the wrong section, I didn't see sddm as a reportable product.
Looks like an SDDM bug to me, please file there: https://github.com/sddm/sddm/issues
I can confirm this issue on newest KDE Neon.
Sorry, I was writing on wrong tab ;)