I have a strange problem. I'm running a Debian testing installation and recently with KDE5 update stream, I got SDDM instead of KDM. However, SDDM does not log me in even when I enter my correct password. When I enter my password:
- SDDM disappears and looks like login is starting.
- After some time, SDDM re-appears.
However, if I shutdown SDDM, start X from my user, export display and run
startkde, I can use KDE as usual.
The logs doesn't show anything worthy.
Any help is appreciated.
Update 1: Running SDDM from console creates no logs on the console. Other logs (syslog, messages, et al.) show that SDDM tries to start the session, but the session just quits. Strange.
Update 2: I found the relevant log entry:
Auth: sddm-helper exited with 2. Which means
pam_backend->openSession() somehow gives an error and exits. However, everything is fine with PAM, groups, file permissions and other details. I cannot trace it to the real reason yet, because SDDM logging doesn't help much.
Update 2.1: Looks like it's related with
PAM, but PAM stack doesn't give any visible errors.