g_object_unref: assertion 'G_IS_OBJECT (object)' failed

[Jaken]

lightdm work fine with xfce4(arch linux),but when i check it's status by systemd,it show this message.

Jun 21 15:55:38 archlinux systemd[1]: Starting Light Display Manager...
Jun 21 15:55:38 archlinux systemd[1]: Started Light Display Manager.
Jun 21 15:55:38 archlinux lightdm[417]: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
Jun 21 15:55:38 archlinux lightdm[465]: pam_unix(lightdm-greeter:session): session opened for user lightdm by (uid
Jun 21 15:55:47 archlinux lightdm[417]: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
Jun 21 15:55:47 archlinux lightdm[607]: pam_unix(lightdm:session): session opened for user jaken by (uid=0)
Jun 21 17:58:33 archlinux lightdm[417]: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

[Robert Ancell (robert-ancell)]

Can you attach /var/log/lightdm/lightdm.log - that might give a better idea where this is occurring.

[Matthew Buttner (koolcharisma)]

I'm having the exact and/or similar problem, but I'm running on an Arch based distro. My Log is as follows:

[+0.09s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.09s] DEBUG: Starting Light Display Manager 1.24.0, UID=0 PID=488
[+0.09s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+0.09s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d
[+0.09s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.09s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.09s] DEBUG: Registered seat module local
[+0.09s] DEBUG: Registered seat module xremote
[+0.09s] DEBUG: Registered seat module unity
[+0.09s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.09s] DEBUG: Monitoring logind for seats
[+0.09s] DEBUG: New seat added from logind: seat0
[+0.09s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.09s] DEBUG: Seat seat0: Starting
[+0.09s] DEBUG: Seat seat0: Creating greeter session
[+0.15s] DEBUG: Seat seat0: Creating display server of type x
[+0.15s] DEBUG: Could not run plymouth --ping: Failed to execute child process “plymouth” (No such file or directory)
[+0.15s] DEBUG: Using VT 7
[+0.15s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.15s] DEBUG: XServer 0: Logging to /var/log/lightdm/x-0.log
[+0.19s] DEBUG: XServer 0: Writing X server authority to /run/lightdm/root/:0
[+0.19s] DEBUG: XServer 0: Launching X Server
[+0.19s] DEBUG: Launching process 497: /usr/bin/X :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.19s] DEBUG: XServer 0: Waiting for ready signal from X server :0
[+0.19s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.19s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+3.10s] DEBUG: Loading users from org.freedesktop.Accounts
[+3.10s] DEBUG: User /org/freedesktop/Accounts/User1000 added
[+7.73s] DEBUG: Got signal 10 from process 497
[+7.73s] DEBUG: XServer 0: Got signal from X server :0
[+7.73s] DEBUG: XServer 0: Connecting to XServer :0
[+7.73s] CRITICAL: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
[+7.73s] DEBUG: Seat seat0: Display server ready, starting session authentication
[+7.73s] DEBUG: Session pid=524: Started with service 'lightdm-greeter', username 'lightdm'
[+7.94s] DEBUG: Session pid=524: Authentication complete with return value 0: Success
[+7.94s] DEBUG: Seat seat0: Session authenticated, running command
[+7.95s] DEBUG: Launching process 527: /usr/bin/numlockx on
[+8.03s] DEBUG: Process 527 exited with return value 0
[+8.03s] DEBUG: Seat seat0: Exit status of /usr/bin/numlockx on: 0
[+8.03s] DEBUG: Session pid=524: Running command /usr/bin/lightdm-gtk-greeter
[+8.03s] DEBUG: Creating shared data directory /var/lib/lightdm-data/lightdm
[+8.03s] DEBUG: Session pid=524: Logging to /var/log/lightdm/seat0-greeter.log
[+8.47s] DEBUG: Activating VT 7
[+8.47s] DEBUG: Activating login1 session c1
[+8.47s] DEBUG: Seat seat0 changes active session to c1
[+8.47s] DEBUG: Session c1 is already active
[+10.95s] DEBUG: Greeter connected version=1.24.0 api=1 resettable=false
[+12.80s] DEBUG: Greeter start authentication f...

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Christophe Lyon (christophe-lyon)]

Hi,
I've just upgraded my x86_64 laptop to Ubuntu 17.10, and I believe I'm hitting the same problem.

In short, I can't login from the lightdm greeter: it accepts my password, the login process starts and immediately stops and comes back to the lightdm greeter. It worked well before I upgraded....

I had warnings about pam-kwallet.so, which I "solved" by installing libpam-kwallet and libpam-kwallet5 packages, and manually created /lib/security symlink pointing to /lib/x86_64-linux-gnu/security. This fixed the warnings, but not the login problem :(

The next thing I noticed is the error message mentioned in this bug report.
My /var/log/lightdm/lightdm.log file contains:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.01s] DEBUG: Starting Light Display Manager 1.24.0, UID=0 PID=1208
[+0.01s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-log-backup.conf
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
[+0.01s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/60-lightdm-gtk-greeter.conf
[+0.01s] DEBUG: Loading configuration dirs from /usr/local/share/lightdm/lightdm.conf.d
[+0.01s] DEBUG: Loading configuration dirs from /etc/xdg/lightdm/lightdm.conf.d
[+0.01s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf.d/10-xubuntu.conf
[+0.01s] DEBUG: [SeatDefaults] is now called [Seat:*], please update this configuration
[+0.01s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.01s] DEBUG: [SeatDefaults] is now called [Seat:*], please update this configuration
[+0.01s] DEBUG: Registered seat module local
[+0.01s] DEBUG: Registered seat module xremote
[+0.01s] DEBUG: Registered seat module unity
[+0.01s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.20s] DEBUG: Monitoring logind for seats
[+0.20s] DEBUG: New seat added from logind: seat0
[+0.20s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.20s] DEBUG: Seat seat0: Starting
[+0.20s] DEBUG: Seat seat0: Creating greeter session
[+0.20s] DEBUG: Seat seat0: Creating display server of type x
[+0.20s] DEBUG: Seat seat0: Plymouth is running on VT 1, but this is less than the configured minimum of 7 so not replacing it
[+0.20s] DEBUG: Quitting Plymouth
[+0.34s] DEBUG: Using VT 7
[+0.34s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.34s] DEBUG: XServer 0: Logging to /var/log/lightdm/x-0.log
[+0.34s] DEBUG: XServer 0: Writing X server authority to /var/run/lightdm/root/:0
[+0.34s] DEBUG: XServer 0: Launching X Server
[+0.34s] DEBUG: Launching process 1296: /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.34s...