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#1 2021-03-12 17:23:45

emsal
Member
Registered: 2021-03-12
Posts: 2

lightdm fails on startup

Hi all,

Around late 2020/early 2021 lightdm fails to start up automatically every time I reboot. However, I'm able to go to an alternate tty, login, and manually start lightdm via systemctl just fine. I looked at earlier topics as well as the wiki article but my issue doesn't match up with the logind-check-graphical config flag.

Here's the content of the lightdm.log from the time of failure:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.30.0, UID=0 PID=788
[+0.00s] DEBUG: Loading configuration dirs from /usr/share/lightdm/lightdm.conf.d
[+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: Registered seat module local
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: _g_io_module_get_default: Found default implementation local (GLocalVfs) for ‘gio-vfs’
[+0.01s] DEBUG: Monitoring logind for seats
[+0.01s] DEBUG: New seat added from logind: seat0
[+0.01s] DEBUG: Seat seat0: Loading properties from config section Seat:*
[+0.01s] DEBUG: Seat seat0 has property CanMultiSession=no
[+0.01s] DEBUG: Seat seat0: Starting
[+0.01s] DEBUG: Seat seat0: Creating greeter session
[+0.01s] DEBUG: Seat seat0: Creating display server of type x
[+0.01s] DEBUG: Could not run plymouth --ping: Failed to execute child process “plymouth” (No such file or directory)
[+0.01s] DEBUG: Using VT 7
[+0.01s] DEBUG: Seat seat0: Starting local X display on VT 7
[+0.01s] DEBUG: XServer 0: Logging to /var/log/lightdm/x-0.log
[+0.01s] DEBUG: XServer 0: Writing X server authority to /run/lightdm/root/:0
[+0.01s] DEBUG: XServer 0: Launching X Server
[+0.01s] DEBUG: Launching process 801: /usr/bin/X :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.01s] DEBUG: XServer 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/User1000 added
[+0.04s] DEBUG: Process 801 exited with return value 1
[+0.04s] DEBUG: XServer 0: X server stopped
[+0.04s] DEBUG: Releasing VT 7
[+0.04s] DEBUG: XServer 0: Removing X server authority /run/lightdm/root/:0
[+0.04s] DEBUG: Seat seat0: Display server stopped
[+0.04s] DEBUG: Seat seat0: Stopping session
[+0.04s] DEBUG: Seat seat0: Session stopped
[+0.04s] DEBUG: Seat seat0: Stopping display server, no sessions require it
[+0.04s] DEBUG: Seat seat0: Stopping; greeter display server failed to start
[+0.04s] DEBUG: Seat seat0: Stopping
[+0.04s] DEBUG: Seat seat0: Stopped
[+0.04s] DEBUG: Required seat has stopped
[+0.04s] DEBUG: Stopping display manager
[+0.04s] DEBUG: Display manager stopped
[+0.04s] DEBUG: Stopping daemon
[+0.05s] DEBUG: Exiting with return value 1

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#2 2021-03-12 18:10:53

loqs
Member
Registered: 2014-03-06
Posts: 13,443

Re: lightdm fails on startup

Please post the matching Xorg.0.log for the lightdm failure and the contents of /etc/lightdm/lightdm.conf.

Last edited by loqs (2021-03-12 18:11:03)

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#3 2021-03-17 18:59:38

emsal
Member
Registered: 2021-03-12
Posts: 2

Re: lightdm fails on startup

Hi loqs, sorry for the late reply. I reproduced the failure again and have the relevant logs.

Xorg.0.log:

X.Org X Server 1.20.10
X Protocol Version 11, Revision 0
Build Operating System: Linux Arch Linux
Current Operating System: Linux toaster 5.10.16-arch1-1 #1 SMP PREEMPT Sat, 13 Feb 2021 20:50:18 +0000 x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-linux root=UUID=0280c5fb-1d27-4ddf-835b-9071a4931712 rw quiet
Build Date: 14 December 2020  12:10:29PM
 
Current version of pixman: 0.40.0
	Before reporting problems, check http://wiki.x.org
	to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
	(++) from command line, (!!) notice, (II) informational,
	(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Sun Mar 14 10:16:27 2021
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
(EE) 
Fatal server error:
(EE) no screens found(EE) 
(EE) 
Please consult the The X.Org Foundation support 
	 at http://wiki.x.org
 for help. 
(EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
(EE) 
(EE) Server terminated with error (1). Closing log file.

/etc/lightdm/lightdm.conf:

#
# General configuration
#
# start-default-seat = True to always start one seat if none are defined in the configuration
# greeter-user = User to run greeter as
# minimum-display-number = Minimum display number to use for X servers
# minimum-vt = First VT to run displays on
# lock-memory = True to prevent memory from being paged to disk
# user-authority-in-system-dir = True if session authority should be in the system location
# guest-account-script = Script to be run to setup guest account
# logind-check-graphical = True to on start seats that are marked as graphical by logind
# log-directory = Directory to log information to
# run-directory = Directory to put running state in
# cache-directory = Directory to cache to
# sessions-directory = Directory to find sessions
# remote-sessions-directory = Directory to find remote sessions
# greeters-directory = Directory to find greeters
# backup-logs = True to move add a .old suffix to old log files when opening new ones
# dbus-service = True if LightDM provides a D-Bus service to control it
#
[LightDM]
#start-default-seat=true
#greeter-user=lightdm
#minimum-display-number=0
#minimum-vt=7 # Setting this to a value < 7 implies security issues, see FS#46799
#lock-memory=true
#user-authority-in-system-dir=false
#guest-account-script=guest-account
#logind-check-graphical=false
#log-directory=/var/log/lightdm
run-directory=/run/lightdm
#cache-directory=/var/cache/lightdm
#sessions-directory=/usr/share/lightdm/sessions:/usr/share/xsessions:/usr/share/wayland-sessions
#remote-sessions-directory=/usr/share/lightdm/remote-sessions
#greeters-directory=$XDG_DATA_DIRS/lightdm/greeters:$XDG_DATA_DIRS/xgreeters
#backup-logs=true
#dbus-service=true

#
# Seat configuration
#
# Seat configuration is matched against the seat name glob in the section, for example:
# [Seat:*] matches all seats and is applied first.
# [Seat:seat0] matches the seat named "seat0".
# [Seat:seat-thin-client*] matches all seats that have names that start with "seat-thin-client".
#
# type = Seat type (local, xremote)
# pam-service = PAM service to use for login
# pam-autologin-service = PAM service to use for autologin
# pam-greeter-service = PAM service to use for greeters
# xserver-command = X server command to run (can also contain arguments e.g. X -special-option)
# xmir-command = Xmir server command to run (can also contain arguments e.g. Xmir -special-option)
# xserver-config = Config file to pass to X server
# xserver-layout = Layout to pass to X server
# xserver-allow-tcp = True if TCP/IP connections are allowed to this X server
# xserver-share = True if the X server is shared for both greeter and session
# xserver-hostname = Hostname of X server (only for type=xremote)
# xserver-display-number = Display number of X server (only for type=xremote)
# xdmcp-manager = XDMCP manager to connect to (implies xserver-allow-tcp=true)
# xdmcp-port = XDMCP UDP/IP port to communicate on
# xdmcp-key = Authentication key to use for XDM-AUTHENTICATION-1 (stored in keys.conf)
# greeter-session = Session to load for greeter
# greeter-hide-users = True to hide the user list
# greeter-allow-guest = True if the greeter should show a guest login option
# greeter-show-manual-login = True if the greeter should offer a manual login option
# greeter-show-remote-login = True if the greeter should offer a remote login option
# user-session = Session to load for users
# allow-user-switching = True if allowed to switch users
# allow-guest = True if guest login is allowed
# guest-session = Session to load for guests (overrides user-session)
# session-wrapper = Wrapper script to run session with
# greeter-wrapper = Wrapper script to run greeter with
# guest-wrapper = Wrapper script to run guest sessions with
# display-setup-script = Script to run when starting a greeter session (runs as root)
# display-stopped-script = Script to run after stopping the display server (runs as root)
# greeter-setup-script = Script to run when starting a greeter (runs as root)
# session-setup-script = Script to run when starting a user session (runs as root)
# session-cleanup-script = Script to run when quitting a user session (runs as root)
# autologin-guest = True to log in as guest by default
# autologin-user = User to log in with by default (overrides autologin-guest)
# autologin-user-timeout = Number of seconds to wait before loading default user
# autologin-session = Session to load for automatic login (overrides user-session)
# autologin-in-background = True if autologin session should not be immediately activated
# exit-on-failure = True if the daemon should exit if this seat fails
#
[Seat:*]
#type=local
#pam-service=lightdm
#pam-autologin-service=lightdm-autologin
#pam-greeter-service=lightdm-greeter
#xserver-command=X
#xmir-command=Xmir
#xserver-config=
#xserver-layout=
#xserver-allow-tcp=false
#xserver-share=true
#xserver-hostname=
#xserver-display-number=
#xdmcp-manager=
#xdmcp-port=177
#xdmcp-key=
#greeter-session=example-gtk-gnome
#greeter-hide-users=false
#greeter-allow-guest=true
#greeter-show-manual-login=false
#greeter-show-remote-login=true
#user-session=default
#allow-user-switching=true
#allow-guest=true
#guest-session=
session-wrapper=/etc/lightdm/Xsession
#greeter-wrapper=
#guest-wrapper=
#display-setup-script=
#display-stopped-script=
#greeter-setup-script=
#session-setup-script=
#session-cleanup-script=
#autologin-guest=false
#autologin-user=
#autologin-user-timeout=0
#autologin-in-background=false
#autologin-session=
#exit-on-failure=false

#
# XDMCP Server configuration
#
# enabled = True if XDMCP connections should be allowed
# port = UDP/IP port to listen for connections on
# listen-address = Host/address to listen for XDMCP connections (use all addresses if not present)
# key = Authentication key to use for XDM-AUTHENTICATION-1 or blank to not use authentication (stored in keys.conf)
# hostname = Hostname to report to XDMCP clients (defaults to system hostname if unset)
#
# The authentication key is a 56 bit DES key specified in hex as 0xnnnnnnnnnnnnnn.  Alternatively
# it can be a word and the first 7 characters are used as the key.
#
[XDMCPServer]
#enabled=false
#port=177
#listen-address=
#key=
#hostname=

#
# VNC Server configuration
#
# enabled = True if VNC connections should be allowed
# command = Command to run Xvnc server with
# port = TCP/IP port to listen for connections on
# listen-address = Host/address to listen for VNC connections (use all addresses if not present)
# width = Width of display to use
# height = Height of display to use
# depth = Color depth of display to use
#
[VNCServer]
#enabled=false
#command=Xvnc
#port=5900
#listen-address=
#width=1024
#height=768
#depth=8

Thank you very much for your help.

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#4 2021-03-17 19:54:19

loqs
Member
Registered: 2014-03-06
Posts: 13,443

Re: lightdm fails on startup

If in /etc/lightdm/lightdm.conf you uncomment:

#logind-check-graphical=false

and change it to

logind-check-graphical=true

then retest that does not have any effect?

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#5 2021-03-18 07:28:08

u666sa
Member
Registered: 2020-08-01
Posts: 38

Re: lightdm fails on startup

Go ahead and create a script file

#! /bin/sh
xrandr --current >> ~/Desktop/file.txt

Save it in /etc/lightdm/display-current.sh

make it executable

sudo chmod +x /etc/lightdm/display-current.sh

Edit /etc/lightdm/lightdm.conf, in [Seat:*] uncomment display-setup-script and make it
display-setup-script=/etc/lightdm/display-current.sh

Reboot couple of times so it fails. Then go to that file.txt on your Desktop and post it's contents here.

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#6 2021-03-18 07:38:15

seth
Member
Registered: 2012-09-03
Posts: 21,093

Re: lightdm fails on startup

#3 suggests the X11 server fails to start, the reason is likely explained in #4 and possibly can be mitigated by https://wiki.archlinux.org/index.php/Ke … _KMS_start
The display-setup-script should™ thus not be reached and if lightdm would execute it nevertheless, it'd just tell you that xrandr can't contact the X11 server.

The XOrg log in #3 looks abbreviated, though - but idk. whether lightdm lowers the log level for the server.

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#7 2021-04-19 06:37:43

regulator
Member
Registered: 2020-01-15
Posts: 1

Re: lightdm fails on startup

loqs wrote:

If in /etc/lightdm/lightdm.conf you uncomment:

#logind-check-graphical=false

and change it to

logind-check-graphical=true

then retest that does not have any effect?

Hey, I had the same issue as OP after installing a RX 6700 XT.. changing that graphical check resolved my issue - thanks!

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