mjhjmtu

Everything works as root. I can startx, and get into iceWM.
I'll be using i3, but that works aswell through lightdm if I login as "other" then write "root".

Loging in in a TTY works aswell, but only as root. When I try loging in as a user, it hangs for a moment, and go back to exactly the way it was before.

When I login as root in a TTY and do su mats, I get su: failed to execute /usr/bin/fish: No such file or directory There is no file there, the directory /usr/bin is there.

Here's the results of #journalctl -f while trying to open i3 through lightdm as a normal user.

nux-v80v:~ # journalctl -f
-- Logs begin at Wed 2019-01-16 15:40:46 CET. --
Jan 16 15:44:27 linux-v80v dbus-daemon[2587]: [session uid=469 pid=2587] Successfully activated service 'org.a11y.Bus'
Jan 16 15:44:27 linux-v80v systemd[2571]: Started Accessibility services bus.
Jan 16 15:44:27 linux-v80v at-spi-bus-launcher[2588]: dbus-daemon[2593]: Activating service name='org.a11y.atspi.Registry' requested by ':1.0' (uid=469 pid=2577 comm="/usr/sbin/lightdm-gtk-greeter ")
Jan 16 15:44:27 linux-v80v dbus-daemon[2587]: [session uid=469 pid=2587] Activating via systemd: service name='org.gtk.vfs.Daemon' unit='gvfs-daemon.service' requested by ':1.3' (uid=469 pid=2577 comm="/usr/sbin/lightdm-gtk-greeter ")
Jan 16 15:44:27 linux-v80v at-spi-bus-launcher[2588]: dbus-daemon[2593]: Successfully activated service 'org.a11y.atspi.Registry'
Jan 16 15:44:27 linux-v80v at-spi-bus-launcher[2588]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Jan 16 15:44:27 linux-v80v systemd[2571]: Starting Virtual filesystem service...
Jan 16 15:44:27 linux-v80v chronyd[1535]: Selected source 185.175.56.126
Jan 16 15:44:27 linux-v80v dbus-daemon[2587]: [session uid=469 pid=2587] Successfully activated service 'org.gtk.vfs.Daemon'
Jan 16 15:44:27 linux-v80v systemd[2571]: Started Virtual filesystem service.
Jan 16 15:44:51 linux-v80v systemd[1]: session-5.scope: Killing process 2561 (lightdm) with signal SIGTERM.
Jan 16 15:44:51 linux-v80v systemd[1]: session-5.scope: Killing process 2577 (lightdm-gtk-gre) with signal SIGTERM.
Jan 16 15:44:51 linux-v80v systemd[1]: Stopping Session 5 of user lightdm.
Jan 16 15:44:51 linux-v80v lightdm[2561]: pam_unix(lightdm-greeter:session): session closed for user lightdm
Jan 16 15:44:51 linux-v80v systemd[1]: Stopped Session 5 of user lightdm.
Jan 16 15:44:51 linux-v80v systemd-logind[1532]: Removed session 5.
Jan 16 15:44:51 linux-v80v systemd[1]: Stopping User Manager for UID 469...
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopping Accessibility services bus...
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopping D-Bus User Message Bus...
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped target Default.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopping Virtual filesystem service...
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped D-Bus User Message Bus.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped Accessibility services bus.
Jan 16 15:44:51 linux-v80v lightdm[1995]: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
Jan 16 15:44:51 linux-v80v systemd[1]: Created slice User Slice of mats.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped Virtual filesystem service.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped target Basic System.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped target Timers.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped target Sockets.
Jan 16 15:44:51 linux-v80v systemd[2571]: Closed D-Bus User Message Bus Socket.
Jan 16 15:44:51 linux-v80v systemd[2571]: Stopped target Paths.
Jan 16 15:44:51 linux-v80v systemd[2571]: Reached target Shutdown.
Jan 16 15:44:51 linux-v80v systemd[2571]: Starting Exit the Session...
Jan 16 15:44:51 linux-v80v systemd[1]: Starting User Manager for UID 1000...
Jan 16 15:44:51 linux-v80v systemd-logind[1532]: New session 6 of user mats.
Jan 16 15:44:51 linux-v80v systemd[2571]: Received SIGRTMIN+24 from PID 2636 (kill).
Jan 16 15:44:51 linux-v80v systemd[1]: Started Session 6 of user mats.
Jan 16 15:44:51 linux-v80v systemd[2635]: pam_unix(systemd-user:session): session opened for user mats by (uid=0)
Jan 16 15:44:51 linux-v80v systemd[2635]: Reached target Paths.
Jan 16 15:44:51 linux-v80v systemd[2635]: Reached target Timers.
Jan 16 15:44:51 linux-v80v systemd[2572]: pam_unix(systemd-user:session): session closed for user lightdm
Jan 16 15:44:51 linux-v80v systemd[2635]: Starting D-Bus User Message Bus Socket.
Jan 16 15:44:51 linux-v80v systemd[1]: Stopped User Manager for UID 469.
Jan 16 15:44:51 linux-v80v systemd[1]: Removed slice User Slice of lightdm.
Jan 16 15:44:51 linux-v80v systemd[2635]: Listening on D-Bus User Message Bus Socket.
Jan 16 15:44:51 linux-v80v systemd[2635]: Reached target Sockets.
Jan 16 15:44:51 linux-v80v systemd[2635]: Reached target Basic System.
Jan 16 15:44:51 linux-v80v systemd[2635]: Reached target Default.
Jan 16 15:44:51 linux-v80v systemd[2635]: Startup finished in 26ms.
Jan 16 15:44:51 linux-v80v lightdm[2619]: pam_unix(lightdm:session): session opened for user mats by (uid=0)
Jan 16 15:44:51 linux-v80v systemd[1]: Started User Manager for UID 1000.
Jan 16 15:44:51 linux-v80v systemd[2635]: Started D-Bus User Message Bus.
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Jan 16 15:48:12 linux-v80v lightdm[2619]: pam_unix(lightdm:session): session closed for user mats
Jan 16 15:48:12 linux-v80v systemd-logind[1532]: Removed session 6.
Jan 16 15:48:12 linux-v80v systemd[1]: Stopping User Manager for UID 1000...
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopping D-Bus User Message Bus...
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopped target Default.
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopped D-Bus User Message Bus.
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopped target Basic System.
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopped target Timers.
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopped target Sockets.
Jan 16 15:48:12 linux-v80v systemd[2635]: Stopped target Paths.
Jan 16 15:48:12 linux-v80v systemd[2635]: Closed D-Bus User Message Bus Socket.
Jan 16 15:48:12 linux-v80v systemd[2635]: Reached target Shutdown.
Jan 16 15:48:12 linux-v80v systemd[2635]: Starting Exit the Session...
Jan 16 15:48:12 linux-v80v systemd[2635]: Received SIGRTMIN+24 from PID 2734 (kill).
Jan 16 15:48:12 linux-v80v systemd[2637]: pam_unix(systemd-user:session): session closed for user mats
Jan 16 15:48:12 linux-v80v systemd[1]: Stopped User Manager for UID 1000.
Jan 16 15:48:12 linux-v80v systemd[1]: Removed slice User Slice of mats.
Jan 16 15:48:13 linux-v80v lightdm[1995]: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
Jan 16 15:48:13 linux-v80v systemd[1]: Created slice User Slice of lightdm.
Jan 16 15:48:13 linux-v80v systemd[1]: Starting User Manager for UID 469...
Jan 16 15:48:13 linux-v80v systemd-logind[1532]: New session 7 of user lightdm.
Jan 16 15:48:13 linux-v80v systemd[1]: Started Session 7 of user lightdm.
Jan 16 15:48:13 linux-v80v systemd[2758]: pam_unix(systemd-user:session): session opened for user lightdm by (uid=0)
Jan 16 15:48:13 linux-v80v systemd[2758]: Reached target Paths.
Jan 16 15:48:13 linux-v80v systemd[2758]: Reached target Timers.
Jan 16 15:48:13 linux-v80v systemd[2758]: Starting D-Bus User Message Bus Socket.
Jan 16 15:48:13 linux-v80v systemd[2758]: Listening on D-Bus User Message Bus Socket.
Jan 16 15:48:13 linux-v80v systemd[2758]: Reached target Sockets.
Jan 16 15:48:13 linux-v80v systemd[2758]: Reached target Basic System.
Jan 16 15:48:13 linux-v80v systemd[2758]: Reached target Default.
Jan 16 15:48:13 linux-v80v systemd[2758]: Startup finished in 23ms.
Jan 16 15:48:13 linux-v80v systemd[1]: Started User Manager for UID 469.
Jan 16 15:48:13 linux-v80v lightdm[2748]: pam_unix(lightdm-greeter:session): session opened for user lightdm by (uid=0)
Jan 16 15:48:13 linux-v80v systemd[2758]: Started D-Bus User Message Bus.
Jan 16 15:48:13 linux-v80v dbus-daemon[2774]: [session uid=469 pid=2774] Activating systemd to hand-off: service name='org.a11y.Bus' unit='at-spi-dbus-bus.service' requested by ':1.0' (uid=469 pid=2764 comm="/usr/sbin/lightdm-gtk-greeter ")
Jan 16 15:48:13 linux-v80v dbus-daemon[2774]: [session uid=469 pid=2774] Successfully activated service 'org.freedesktop.systemd1'
Jan 16 15:48:13 linux-v80v systemd[2758]: Starting Accessibility services bus...
Jan 16 15:48:13 linux-v80v dbus-daemon[2774]: [session uid=469 pid=2774] Successfully activated service 'org.a11y.Bus'
Jan 16 15:48:13 linux-v80v systemd[2758]: Started Accessibility services bus.
Jan 16 15:48:13 linux-v80v at-spi-bus-launcher[2775]: dbus-daemon[2780]: Activating service name='org.a11y.atspi.Registry' requested by ':1.0' (uid=469 pid=2764 comm="/usr/sbin/lightdm-gtk-greeter ")
Jan 16 15:48:13 linux-v80v dbus-daemon[2774]: [session uid=469 pid=2774] Activating via systemd: service name='org.gtk.vfs.Daemon' unit='gvfs-daemon.service' requested by ':1.3' (uid=469 pid=2764 comm="/usr/sbin/lightdm-gtk-greeter ")
Jan 16 15:48:13 linux-v80v systemd[2758]: Starting Virtual filesystem service...
Jan 16 15:48:13 linux-v80v at-spi-bus-launcher[2775]: dbus-daemon[2780]: Successfully activated service 'org.a11y.atspi.Registry'
Jan 16 15:48:13 linux-v80v at-spi-bus-launcher[2775]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Jan 16 15:48:13 linux-v80v dbus-daemon[2774]: [session uid=469 pid=2774] Successfully activated service 'org.gtk.vfs.Daemon'
Jan 16 15:48:13 linux-v80v systemd[2758]: Started Virtual filesystem service

As @Mark pointed out, the problem was that it couldn't find the fish shell.

It was just a matter of specifying the path to a shell

I had to reinstall the shell. (As if there was none installed, which I find a bit strange for something like openSUSE.)

zypper install fish

If that doesn't work, you can also specify where the shell is. (After making sure it's installed.)

Type chsh *username* in a TTY (after loging in) and type usr/bin/fish.
(Or the path to the shell you are using, I use zsh, so that's /usr/bin/zsh.)