3

My system is refusing to allow me to log out from my gnome session when I click the "Log Out" button. I can log in just fine, and the session appears to work okay. However, when I attempt to log out (or type "gnome-session-quit" at a terminal), I am ultimately brought back to a fresh session.

UPDATE: Eventually, the system will let me log out, but I have to log out four times. lightdm --session-child appears to be spawned multiple times, but once it has been cleared, I can log out.

UPDATE 2: Added some information from the syslog, showing that dbus is rejecting "ReleaseSession" from the lightdm --session-child process. I think this has to be some kind of permission thing, but I'm not sure where to look or how to reset it.

I am running 16.04.5 LTS, kernel 4.4.0-130-generic, and I have the nvidia-384 drivers installed.

Some notes:

  • Open applications are closed, and the Unity/Gnome display goes away after a confirm that I want to log out. I'm left with a desktop background for a few seconds, then the Unity/Gnome interface pops up again, just like I had started a new session.
  • This behavior occurs when I use both Gnome (gnome.desktop) and Ubuntu/Unity (ubuntu.desktop) sessions.
  • The behavior does not occur when I use gdm3, only lightdm.
  • I have tried cleaning out lightdm, removing the contents of /var/lightdm, and resetting the files in /etc/lightdm. I've uninstalled and reinstalled lightdm as well as tried dpkg-reconfigure lightdm. No luck.
  • The problem occurs for old users as well as newly-created users.
  • The behavior is the same using the "nvidia-340" drivers.
  • I have also attempted uninstalling and reinstalling xinit and gnome to no avail. Again, the session lets me log in, but I can't seem to log out.
  • Unfortunately, I'm not quite sure when the behavior started, so I can't trace it to a particular update or system change. Certainly within the past two months.

I'm not exactly sure where to start with the logs. However, I've included the results from /var/log/lightdm.

Thanks in advance for any help.

UPDATE 2: Here are the entries from syslog. There a quite a few of these:

    dbus: [system] Rejected send message, 2 matched rules; type="method_call", sender=":1.121" (uid=1046 pid=3079 comm="lightdm --session-child 12 19 ") interface="org.freedesktop.login1.Manager" member="ReleaseSession" error name="(unset)" requested_reply="0" destination="org.freedesktop.login1" (uid=0 pid=1148 comm="/lib/systemd/systemd-logind "): 1 Time(s)
    dbus: [system] Rejected send message, 2 matched rules; type="method_call", sender=":1.126" (uid=1046 pid=2640 comm="lightdm --session-child 12 19 ") interface="org.freedesktop.login1.Manager" member="ReleaseSession" error name="(unset)" requested_reply="0" destination="org.freedesktop.login1" (uid=0 pid=1142 comm="/lib/systemd/systemd-logind "): 1 Time(s)

UPDATE: As mentioned above, lightdm appears to span multiple lightdm --session-child processes. I have a similar system that behaves normally. On that system, after login, only one process exists after login, and it is owned by root (for the greeter?). On my system, two lightdm --session-child processes exist after login, and are owned by the user. See below for a freshly-created user (fresh):

Session-child processes before login:

root      1530  1442  0 11:03 ?        00:00:00 lightdm --session-child 16 19
root      1647  1442  0 11:03 ?        00:00:00 lightdm --session-child 12 19

Session-child processes after the first login:

root      1647  1442  0 11:03 ?        00:00:00 lightdm --session-child 12 19
fresh     3109  1647  0 11:04 ?        00:00:00 lightdm --session-child 12 19
fresh     3110  3109  0 11:04 ?        00:00:00 lightdm --session-child 12 19

Session-child processes after the first logout attempt:

root      1647  1442  0 11:03 ?        00:00:00 lightdm --session-child 12 19
fresh     3109  1647  0 11:04 ?        00:00:00 lightdm --session-child 12 19

Session-child processes after the second logout attempt:

root      1647  1442  0 11:03 ?        00:00:00 lightdm --session-child 12 19
fresh     4470  1647  0 11:06 ?        00:00:00 lightdm --session-child 12 19

Session-child processes after the third logout attempt. On a normal system, a single session-child process, owned by root, is the typical result after the user logs in. On my system, I have to log out three times to get down to this point:

root      1647  1442  0 11:03 ?        00:00:00 lightdm --session-child 12 19

Session-child processes after the fourth logout attempt (a successful logout):

root      5723  1442  0 11:08 ?        00:00:00 lightdm --session-child 16 19
root      5775  1442  0 11:08 ?        00:00:00 lightdm --session-child 12 19

I have no idea why so many of these processes are being spawned, or why they refuse to die. Worse, I have no idea where to look for what might be causing the hangup. I see nothing obvious in the lightdm logs.

lightdm.log:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.18.3, UID=0 PID=12609
[+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-log-backup.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/90-nvidia.conf
[+0.00s] DEBUG:   [SeatDefaults] is now called [Seat:*], please update this configuration
[+0.00s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Registered seat module unity
[+0.00s] DEBUG: Monitoring logind for seats
[+0.00s] DEBUG: New seat added from logind: seat0
[+0.00s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.00s] DEBUG: Seat seat0: Starting
[+0.00s] DEBUG: Seat seat0: Creating greeter session
[+0.00s] DEBUG: Seat seat0: Creating display server of type x
[+0.00s] DEBUG: Using VT 7
[+0.00s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.00s] DEBUG: DisplayServer x-0: Logging to /var/log/lightdm/x-0.log
[+0.00s] DEBUG: DisplayServer x-0: Writing X server authority to /var/run/lightdm/root/:0
[+0.00s] DEBUG: DisplayServer x-0: Launching X Server
[+0.00s] DEBUG: Launching process 12616: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.00s] DEBUG: DisplayServer x-0: Waiting for ready signal from X server :0
[+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.01s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.01s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User3004 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User5008 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User5015 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User1045 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User1004 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User1019 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User5007 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User1009 added
[+0.01s] DEBUG: User /org/freedesktop/Accounts/User5006 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1063 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User5013 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1023 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1032 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1064 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1108 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User5000 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1102 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User5001 added
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User1101 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User1069 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User1013 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User1084 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User1027 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User1104 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User5010 added
[+0.03s] DEBUG: User /org/freedesktop/Accounts/User1030 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1016 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1025 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1099 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1047 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1058 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User5009 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1038 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1087 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1079 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User3002 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1066 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1103 added
[+0.04s] DEBUG: User /org/freedesktop/Accounts/User1074 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User2000 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1096 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1075 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1098 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1052 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1035 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1053 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1097 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1044 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1010 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User3001 added
[+0.05s] DEBUG: User /org/freedesktop/Accounts/User1076 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1050 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User3005 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1081 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1061 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1036 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1089 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1011 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1086 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1083 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1021 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1095 added
[+0.06s] DEBUG: User /org/freedesktop/Accounts/User1056 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1001 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1073 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1031 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User5004 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1015 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1065 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User5003 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1042 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1088 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1067 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1059 added
[+0.07s] DEBUG: User /org/freedesktop/Accounts/User1092 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1039 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1024 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User5011 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1051 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1012 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User5002 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1093 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1043 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1070 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1040 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1014 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1062 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User1100 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1078 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1007 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1090 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1000 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1080 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1094 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1091 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1060 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User3003 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1105 added
[+0.09s] DEBUG: User /org/freedesktop/Accounts/User1057 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1006 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1071 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User3000 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1005 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1106 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1034 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1008 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1022 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1072 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1018 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User5012 added
[+0.10s] DEBUG: User /org/freedesktop/Accounts/User1046 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1055 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User5014 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1041 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1028 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1077 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1082 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1003 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1048 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1029 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1033 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1054 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1020 added
[+0.11s] DEBUG: User /org/freedesktop/Accounts/User1037 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1049 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User5005 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1107 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1068 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1002 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1085 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1026 added
[+0.12s] DEBUG: User /org/freedesktop/Accounts/User1017 added
[+0.12s] DEBUG: Seat seat0 changes active session to 
[+0.12s] CRITICAL: session_get_login1_session_id: assertion 'session != NULL' failed
[+0.67s] DEBUG: Got signal 10 from process 12616
[+0.67s] DEBUG: DisplayServer x-0: Got signal from X server :0
[+0.67s] DEBUG: DisplayServer x-0: Connecting to XServer :0
[+0.67s] DEBUG: Launching process 12631: /sbin/prime-offload
[+0.68s] DEBUG: Process 12631 exited with return value 0
[+0.68s] DEBUG: Seat seat0: Exit status of /sbin/prime-offload: 0
[+0.68s] DEBUG: Seat seat0: Display server ready, starting session authentication
[+0.68s] DEBUG: Session pid=12637: Started with service 'lightdm-greeter', username 'lightdm'
[+0.84s] DEBUG: Session pid=12637: Authentication complete with return value 0: Success
[+0.84s] DEBUG: Seat seat0: Session authenticated, running command
[+0.84s] DEBUG: Session pid=12637: Running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter
[+0.84s] DEBUG: Creating shared data directory /var/lib/lightdm-data/lightdm
[+0.84s] DEBUG: Session pid=12637: Logging to /var/log/lightdm/seat0-greeter.log
[+0.90s] DEBUG: Activating VT 7
[+0.90s] DEBUG: Activating login1 session c4
[+0.90s] DEBUG: Seat seat0 changes active session to c4
[+0.90s] DEBUG: Session c4 is already active
[+1.02s] DEBUG: Greeter connected version=1.18.3 resettable=false
[+1.07s] DEBUG: Greeter start authentication
[+1.07s] DEBUG: Session pid=12698: Started with service 'lightdm', username '(null)'
[+1.07s] DEBUG: Session pid=12698: Got 1 message(s) from PAM
[+1.07s] DEBUG: Prompt greeter with 1 message(s)
[+10.84s] DEBUG: Continue authentication
[+10.84s] DEBUG: Session pid=12698: Got 1 message(s) from PAM
[+10.84s] DEBUG: Prompt greeter with 1 message(s)
[+12.90s] DEBUG: Continue authentication
[+13.31s] DEBUG: Session pid=12698: Authentication complete with return value 0: Success
[+13.31s] DEBUG: Authenticate result for user fresh: Success
[+13.31s] DEBUG: User fresh authorized
[+13.31s] DEBUG: Greeter requests default session
[+13.31s] DEBUG: Seat seat0: Stopping greeter; display server will be re-used for user session
[+13.31s] DEBUG: Session pid=12637: Sending SIGTERM
[+13.33s] DEBUG: Greeter closed communication channel
[+13.33s] DEBUG: Session pid=12637: Exited with return value 0
[+13.33s] DEBUG: Seat seat0: Session stopped
[+13.33s] DEBUG: Seat seat0: Greeter stopped, running session
[+13.33s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0
[+13.33s] DEBUG: Session pid=12698: Running command /usr/sbin/lightdm-session gnome-session --session=ubuntu
[+13.33s] DEBUG: Creating shared data directory /var/lib/lightdm-data/fresh
[+13.33s] DEBUG: Session pid=12698: Logging to .xsession-errors

seat0-greeter.log:


** (process:12666): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files
[+0.00s] DEBUG: unity-greeter.vala:502: Starting unity-greeter 16.04.2 UID=118 LANG=en_US.UTF-8
[+0.00s] DEBUG: unity-greeter.vala:505: Setting cursor
Activating service name='org.a11y.atspi.Registry'
[+0.00s] DEBUG: unity-greeter.vala:519: Loading command line options
[+0.00s] DEBUG: unity-greeter.vala:547: Setting GTK+ settings
Successfully activated service 'org.a11y.atspi.Registry'
[+0.04s] DEBUG: unity-greeter.vala:570: Creating Unity Greeter
[+0.04s] DEBUG: unity-greeter.vala:57: Creating background surface
[+0.04s] DEBUG: Connecting to display manager...
[+0.04s] DEBUG: Wrote 22 bytes to daemon
[+0.04s] DEBUG: Read 8 bytes from daemon
[+0.04s] DEBUG: Read 150 bytes from daemon
[+0.04s] DEBUG: Connected version=1.18.3 default-session=ubuntu show-manual-login=false hide-users=true has-guest-account=false show-remote-login=true
[+0.06s] DEBUG: menubar.vala:335: LANG=en_US.UTF-8 LANGUAGE=(null)
[+0.06s] DEBUG: menubar.vala:367: LANG=en_US.UTF-8 LANGUAGE=(null)
[+0.08s] DEBUG: Loaded session /usr/share/xsessions/ubuntu.desktop (Ubuntu, This session logs you into Ubuntu)
[+0.08s] DEBUG: Loaded session /usr/share/xsessions/gnome-classic.desktop (GNOME Classic, This session logs you into GNOME Classic)
[+0.08s] DEBUG: Loaded session /usr/share/xsessions/gnome.desktop (GNOME, This session logs you into GNOME)
[+0.08s] DEBUG: Starting authentication for user (null)...
[+0.08s] DEBUG: Wrote 16 bytes to daemon
[+0.11s] DEBUG: main-window.vala:185: Screen is 3840x1200 pixels
[+0.11s] DEBUG: main-window.vala:193: Monitor 0 is 1920x1200 pixels at 0,0
[+0.11s] DEBUG: main-window.vala:193: Monitor 1 is 1920x1200 pixels at 1920,0
[+0.11s] DEBUG: unity-greeter.vala:573: Showing greeter
[+0.11s] DEBUG: unity-greeter.vala:257: Showing main window
[+0.11s] DEBUG: background.vala:483: Regenerating backgrounds
[+0.11s] DEBUG: background.vala:68: Making background /usr/share/backgrounds/warty-final-ubuntu.png at 1920x1200
[+0.12s] DEBUG: unity-greeter.vala:616: Starting main loop
[+0.12s] DEBUG: Read 8 bytes from daemon
[+0.12s] DEBUG: Read 26 bytes from daemon
[+0.12s] DEBUG: Prompt user with 1 message(s)
[+0.13s] DEBUG: settings-daemon.vala:75: Acquired org.gnome.SessionManager
[+0.13s] DEBUG: settings-daemon.vala:102: Acquired org.gnome.ScreenSaver
[+0.13s] DEBUG: settings-daemon.vala:159: All bus names acquired, starting unity-settings-daemon
[+0.16s] DEBUG: menubar.vala:537: Adding indicator object 0x18df5b0 at position 0
[+0.16s] DEBUG: unity-greeter.vala:240: starting system-ready sound

(nm-applet:12704): GLib-GObject-WARNING **: invalid unclassed pointer in cast to 'GtkWidget'

(nm-applet:12704): Gtk-CRITICAL **: gtk_widget_show: assertion 'GTK_IS_WIDGET (widget)' failed
[+2.87s] DEBUG: Connected to Application Indicator Service.
[+2.88s] DEBUG: menubar.vala:537: Adding indicator object 0x18df450 at position 0
[+2.88s] DEBUG: menubar.vala:537: Adding indicator object 0x18df710 at position 2
[+2.88s] DEBUG: menubar.vala:537: Adding indicator object 0x18df2f0 at position 3
[+2.89s] DEBUG: menubar.vala:537: Adding indicator object 0x18df870 at position 2
[+2.89s] DEBUG: Request current apps
[+2.96s] DEBUG: Building new application entry: :1.14  with icon: nm-device-wired at position 0
[+2.96s] DEBUG: menubar.vala:537: Adding indicator object 0x19dc5f0 at position 5
[+2.96s] DEBUG: background.vala:121: Render of background /usr/share/backgrounds/warty-final-ubuntu.png complete

** (unity-settings-daemon:12723): WARNING **: Unable to register client: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method 'RegisterClient'
[+9.85s] DEBUG: Providing response to display manager
[+9.86s] DEBUG: Wrote 21 bytes to daemon
[+9.86s] DEBUG: Read 8 bytes from daemon
[+9.86s] DEBUG: Read 35 bytes from daemon
[+9.86s] DEBUG: Prompt user with 1 message(s)
[+11.91s] DEBUG: Providing response to display manager
[+11.91s] DEBUG: Wrote 24 bytes to daemon
[+12.33s] DEBUG: Read 8 bytes from daemon
[+12.33s] DEBUG: Read 17 bytes from daemon
[+12.33s] DEBUG: Authentication complete for user fresh with return code 0
[+12.33s] DEBUG: Starting default session
[+12.33s] DEBUG: Wrote 12 bytes to daemon
[+12.33s] DEBUG: Read 8 bytes from daemon
[+12.33s] DEBUG: Read 4 bytes from daemon

** (unity-settings-daemon:12723): WARNING **: Name taken or bus went away - shutting down
[+12.33s] DEBUG: unity-greeter.vala:611: Got a SIGTERM
[+12.33s] DEBUG: settings-daemon.vala:78: Failed to acquire name org.gnome.SessionManager
[+12.33s] DEBUG: settings-daemon.vala:105: Failed to acquire name org.gnome.ScreenSaver
upstart: indicator-messages main process ended, respawning
upstart: indicator-bluetooth main process (12707) killed by TERM signal
upstart: indicator-bluetooth main process ended, respawning
upstart: indicator-datetime main process (12709) killed by TERM signal
upstart: indicator-datetime main process ended, respawning
[+12.33s] DEBUG: unity-greeter.vala:135: Failed to acquire name com.canonical.Unity
upstart: indicator-sound main process ended, respawning
[+12.33s] DEBUG: unity-greeter.vala:619: Cleaning up
upstart: indicator-session main process (12712) killed by TERM signal
[+12.33s] DEBUG: unity-greeter.vala:627: Upstart exited with return value 0
upstart: indicator-session main process ended, respawning
[+12.33s] DEBUG: unity-greeter.vala:639: AT-SPI exited with return value 0
[+12.33s] DEBUG: unity-greeter.vala:645: Exiting
upstart: indicator-application main process (12726) killed by TERM signal
upstart: indicator-application main process ended, respawning

(unity-settings-daemon:12723): dconf-WARNING **: failed to commit changes to dconf: The connection is closed

(unity-settings-daemon:12723): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(unity-settings-daemon:12723): GLib-GObject-CRITICAL **: g_signal_handlers_disconnect_matched: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

** (unity-settings-daemon:12723): WARNING **: Lost or failed to acquire name org.gnome.Mutter.IdleMonitor

upstart: indicator-power main process (12708) killed by TERM signal
upstart: indicator-bluetooth main process (13189) killed by TERM signal
upstart: indicator-datetime main process (13190) killed by TERM signal
upstart: indicator-sound main process (13191) killed by TERM signal
upstart: indicator-messages main process (13188) killed by TERM signal
upstart: indicator-session main process (13192) killed by TERM signal
2

I had the same problem on my laptop while my desktop PC ran fine with the same setup. The hint which gave me the solution was the difference in

systemctl status lightdm

When I uninstalled pam-kwallet on the non-working laptop

apt remove libpam-kwallet-common libpam-kwallet4 libpam-kwallet5

the logoff-problem was gone

0

I too had the same problem: I could not logout from the session I started. I too had two lightdm --session-child processes at login. I did not however do the extended fault search like NickF did. I just took the easy way out and changed the display manager. I chose sddm and now everything is back to normal.

I run 16.04 on a old Dell E6230 (i7-3540M CPU @ 3.00GHz and Intel HD Graphics 4000). I use openbox instead of Unity/Gnome which combined with the fact that I changed DM probably means that it is a lightdm problem.

  • That's been my solution so far - switched to gdm3 with no problems. Open source software is great when it works, but given the amount of time I spent on this I could have purchased Windows several times over. Glad I'm not crazy! – NickF Jul 29 '18 at 18:05

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