Here is additional info.
From terminal as root I stopped kdm.service and started sddm, which
failed to start, reports follow.
This is output of 'systemctl status sddm.service'.
● sddm.service - Simple Desktop Display Manager
Loaded: loaded (/lib/systemd/system/sddm.service; enabled; vendor
preset: enabled)
Active: failed (Result: start-limit) since Sat 2015-09-12 21:52:34
EDT; 12min ago
Docs: man:sddm(1)
man:sddm.conf(5)
Process: 1639 ExecStartPre=/bin/sh -c [ "$(cat
/etc/X11/default-display-manager 2>/dev/null)" = "/usr/bin/sddm" ]
(code=exited, status=1/FAILURE)
Output of 'journal -xe' is much larger, Debian paste would not take it
so had to use pastebin.
pastebin.com/DQ9WBp4Y
After setting sddm as default-display-manager in /etc/X11, and
rebooting, I got a completely black screen.
Had to tty again and set kdm back as default to get normal boot again.
I think that severity is grave since sddm is unusable.
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On 09/16/2015 07:11 AM, Maximiliano Curia wrote:
I couldn't reproduce the bug as reported. But since the log showed
starting sddm from tty1 after an upgrade I tested sddm with a running
display-manager, it fails in similar ways to the reported error.
Either having an X on tty7, an non-stopped kdm, lightdm, or any other
display manager running in tty7 would fail. I think that sddm is
failing to detect the 'seat' already in use. I'll keep on
investigating this issue. In the mean time, it would be nice to if you
could check if stopping a running display manager before starting sddm
allows sddm to work for you, as this would confirm that we are talking
about the same issue. Happy hacking,