[SOLVED] LightDM Greeter fails due to PAM issue
by BoraxMan from LinuxQuestions.org on (#6GG4Q)
I've had a working Fedora setup using LightDM as the display manager for years. Now that I've upgraded Fedora to version 39 from 37, lightdm broke.
I have uninstalled lightdm and all greeters, deleted the configuration at /etc/lightdm as well as anything under /var/lib/lightdm and reinstalled. I am using the supplied configuration with lightdm, changed only to use lightdm-gtk-greeter, but it didn't work even before I touched the config.
When I do start lightdm I get a blank screen (the video mode changes, so X starts), but nothing else. The actual greeter fails to start and lightdm exists.
The logs are below, and the telling one is "seat0-greeter.log" which just has one line. I'm not sure what this means, and how to fix it. Note that the lightdm greeter does not start at all.
Code:Failed to establish PAM credentials: Critical error - immediate abortlightdm.log below
Code:[+0.00s] DEBUG: Logging to /home/user/.cache/lightdm/log/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=500 PID=2738
[+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-backup-logs.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-minimum-vt.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-run-directory.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-session-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-user-authority-in-system-dir.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/60-lightdm-gtk-greeter.conf
[+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: Running in user mode
[+0.00s] DEBUG: Using Xephyr for X servers
[+0.00s] DEBUG: Registered seat module local
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.01s] DEBUG: _g_io_module_get_default: Found default implementation gvfs (GDaemonVfs) for ?gio-vfs?
[+0.01s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.02s] DEBUG: Monitoring logind for seats
[+0.02s] DEBUG: New seat added from logind: seat0
[+0.02s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.02s] DEBUG: Seat seat0 has property CanMultiSession=no
[+0.02s] DEBUG: Seat seat0: Starting
[+0.02s] DEBUG: Seat seat0: Creating greeter session
[+0.02s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User501 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User500 added
[+0.12s] DEBUG: Seat seat0: Creating display server of type x
[+0.13s] DEBUG: Seat seat0: Starting local X display
[+0.13s] DEBUG: XServer 0: Logging to /home/dennisk/.cache/lightdm/log/x-0.log
[+0.13s] WARNING: XServer 0: Failed to make authority directory /run/lightdm/root: Permission denied
[+0.13s] DEBUG: XServer 0: Writing X server authority to /run/lightdm/root/:0
[+0.13s] WARNING: XServer 0: Failed to write authority: Failed to open X authority /run/lightdm/root/:0: No such file or directory
[+0.13s] DEBUG: XServer 0: Launching X Server
[+0.13s] DEBUG: Launching process 2747: /usr/bin/Xephyr :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp
[+0.13s] DEBUG: XServer 0: Waiting for ready signal from X server :0
[+0.13s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.13s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.17s] DEBUG: Process 2747 exited with return value 1
[+0.17s] DEBUG: XServer 0: X server stopped
[+0.17s] DEBUG: XServer 0: Removing X server authority /run/lightdm/root/:0
[+0.17s] DEBUG: Seat seat0: Display server stopped
[+0.17s] DEBUG: Seat seat0: Stopping session
[+0.17s] DEBUG: Seat seat0: Session stopped
[+0.17s] DEBUG: Seat seat0: Stopping display server, no sessions require it
[+0.17s] DEBUG: Seat seat0: Stopping; greeter display server failed to start
[+0.17s] DEBUG: Seat seat0: Stopping
[+0.17s] DEBUG: Seat seat0: Stopped
[+0.17s] DEBUG: Required seat has stopped
[+0.17s] DEBUG: Stopping display manager
[+0.17s] DEBUG: Display manager stopped
[+0.17s] DEBUG: Stopping daemon
[+0.17s] DEBUG: Exiting with return value 1
I have uninstalled lightdm and all greeters, deleted the configuration at /etc/lightdm as well as anything under /var/lib/lightdm and reinstalled. I am using the supplied configuration with lightdm, changed only to use lightdm-gtk-greeter, but it didn't work even before I touched the config.
When I do start lightdm I get a blank screen (the video mode changes, so X starts), but nothing else. The actual greeter fails to start and lightdm exists.
The logs are below, and the telling one is "seat0-greeter.log" which just has one line. I'm not sure what this means, and how to fix it. Note that the lightdm greeter does not start at all.
Code:Failed to establish PAM credentials: Critical error - immediate abortlightdm.log below
Code:[+0.00s] DEBUG: Logging to /home/user/.cache/lightdm/log/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=500 PID=2738
[+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-backup-logs.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-minimum-vt.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-run-directory.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-session-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /usr/share/lightdm/lightdm.conf.d/50-user-authority-in-system-dir.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/60-lightdm-gtk-greeter.conf
[+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: Running in user mode
[+0.00s] DEBUG: Using Xephyr for X servers
[+0.00s] DEBUG: Registered seat module local
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.01s] DEBUG: _g_io_module_get_default: Found default implementation gvfs (GDaemonVfs) for ?gio-vfs?
[+0.01s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.02s] DEBUG: Monitoring logind for seats
[+0.02s] DEBUG: New seat added from logind: seat0
[+0.02s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.02s] DEBUG: Seat seat0 has property CanMultiSession=no
[+0.02s] DEBUG: Seat seat0: Starting
[+0.02s] DEBUG: Seat seat0: Creating greeter session
[+0.02s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.02s] DEBUG: User /org/freedesktop/Accounts/User501 added
[+0.08s] DEBUG: User /org/freedesktop/Accounts/User500 added
[+0.12s] DEBUG: Seat seat0: Creating display server of type x
[+0.13s] DEBUG: Seat seat0: Starting local X display
[+0.13s] DEBUG: XServer 0: Logging to /home/dennisk/.cache/lightdm/log/x-0.log
[+0.13s] WARNING: XServer 0: Failed to make authority directory /run/lightdm/root: Permission denied
[+0.13s] DEBUG: XServer 0: Writing X server authority to /run/lightdm/root/:0
[+0.13s] WARNING: XServer 0: Failed to write authority: Failed to open X authority /run/lightdm/root/:0: No such file or directory
[+0.13s] DEBUG: XServer 0: Launching X Server
[+0.13s] DEBUG: Launching process 2747: /usr/bin/Xephyr :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp
[+0.13s] DEBUG: XServer 0: Waiting for ready signal from X server :0
[+0.13s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.13s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.17s] DEBUG: Process 2747 exited with return value 1
[+0.17s] DEBUG: XServer 0: X server stopped
[+0.17s] DEBUG: XServer 0: Removing X server authority /run/lightdm/root/:0
[+0.17s] DEBUG: Seat seat0: Display server stopped
[+0.17s] DEBUG: Seat seat0: Stopping session
[+0.17s] DEBUG: Seat seat0: Session stopped
[+0.17s] DEBUG: Seat seat0: Stopping display server, no sessions require it
[+0.17s] DEBUG: Seat seat0: Stopping; greeter display server failed to start
[+0.17s] DEBUG: Seat seat0: Stopping
[+0.17s] DEBUG: Seat seat0: Stopped
[+0.17s] DEBUG: Required seat has stopped
[+0.17s] DEBUG: Stopping display manager
[+0.17s] DEBUG: Display manager stopped
[+0.17s] DEBUG: Stopping daemon
[+0.17s] DEBUG: Exiting with return value 1