Unable to switch to greeter

[Adam]

I'm using LightDM 1.16.5 along with the Awesome window manager [1] on NixOS [2].

After logging in, I am unable to switch users without first logging out of my current session. The command `dm-tool switch-to-greeter` has absolutely no effect and gives no output. Same with `dm-tool lock`.

Another command I tried after searching the Internet:

    $ dbus-send --system --type=method_call --print-reply --dest=org.freedesktop.DisplayManager $XDG_SEAT_PATH org.freedesktop.DisplayManager.Seat.SwitchToGreeter
    method return sender=:1.2 -> dest=:1.37 reply_serial=2

Here are some XDG-related environment variables:

    XDG_VTNR=7
    XDG_SESSION_ID=5
    XDG_GREETER_DATA_DIR=/var/lib/lightdm-data/myuser
    XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session1
    XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
    XDG_CONFIG_DIRS=/home/myuser/.nix-profile/etc/xdg:/nix/var/nix/profiles/default/etc/xdg:/run/current-system/sw/etc/xdg
    XDG_SESSION_TYPE=x11
    XDG_SEAT=seat0
    XDG_SESSION_DESKTOP=none + awesome
    XDG_DATA_DIRS=/home/myuser/.nix-profile/share:/nix/var/nix/profiles/default/share:/run/current-system/sw/share
    XDG_RUNTIME_DIR=/run/user/12345

[1] http://awesome.naquadah.org/
[2] http://nixos.org/

[Robert Ancell (robert-ancell)]

Have a look at /var/log/lightdm/lightdm.log after this occurs.

[Adam (adam.russell)]

[+1722432.01s] DEBUG: Seat seat0: Creating greeter session
[+1722432.01s] DEBUG: Seat seat0: Creating display server of type x
[+1722432.01s] DEBUG: Using VT 8
[+1722432.01s] DEBUG: Seat seat0: Starting local X display on VT 8
[+1722432.01s] DEBUG: DisplayServer x-1: Logging to /var/log/x-1.log
[+1722432.01s] DEBUG: DisplayServer x-1: Writing X server authority to /run/root/:1
[+1722432.01s] DEBUG: DisplayServer x-1: Launching X Server
[+1722432.01s] DEBUG: Launching process 11337: /nix/store/2qzyfba6ds1bqnr0i75lhip50wgfq0qn-xserver-wrapper :1 -seat seat0 -auth /run/root/:1 -nolisten tcp vt8 -novtswitch
[+1722432.01s] DEBUG: DisplayServer x-1: Waiting for ready signal from X server :1
[+1722432.02s] DEBUG: Process 11337 exited with return value 1
[+1722432.02s] DEBUG: DisplayServer x-1: X server stopped
[+1722432.02s] DEBUG: Releasing VT 8
[+1722432.02s] DEBUG: DisplayServer x-1: Removing X server authority /run/root/:1
[+1722432.02s] DEBUG: Seat seat0: Display server stopped
[+1722432.02s] DEBUG: Seat seat0: Stopping session
[+1722432.02s] DEBUG: Seat seat0: Session stopped
[+1722432.02s] DEBUG: Seat seat0: Stopping display server, no sessions require it

[Adam (adam.russell)]

And /var/log/x-1.log:

(EE)
Fatal server error:
(EE) Server is already active for display 0
        If this server is no longer running, remove /tmp/.X0-lock
        and start again.
(EE)
(EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
 for help.
(EE)

[Erik R (ridderby)]

I have similar problem on ONE of my computers.

Same kind of error message but in my case the screen will switch to texxt mode and the cursor will blink in a strange frequency, like it is blinking every time a new process is started above.

On this particular computer I am running funtoo current, xfce4, lightdm 1.19.0 and gtk-greeter 2.0.1-r1. If also run kernel 4.6.0 and nouveu drivers for my nvidia card.

On the laptop also running funtoo current but have kernel 4.6.2 and Intel Core I5 Haswell with the very latest haswel graphics things works well. It have the same version of xfce4. lightdm and lightdm-gtk-greeter.

On my second laptop with same setup it also works well. That is an EeePC with atom processor and a GM500 or similar graphics. Xfce and lightdm is same.

Question is why it fails on the workstation and not on any of the laptops with the same os, Xfce4 and lightdm.

How can I help fualt findning? Beside the very same message as shown above?