[SOLVED] Lightdm failing to start when swaping greeter

mu40u_n1k4 · 2025-07-24 15:28:56

Issue

Fresh Arch install. I'm setting up lightdm to use a greeter. If I don't select a greeter, lightdm starts up with it's default greeter just fine. If I swap the greeter (I've tried lightdm-gtk-greeter, lightdm-slick-greeter, web-greeter) it fails. I've provided some information bellow, let me know if there is anything else I can provide. Does anyone know what might be causing this issue?

I'm guessing it has to do with

[+0.00s] DEBUG: Seat seat0: Failed to find session configuration lightdm-slick-greeter

but I'm not sure where to go from there. This error is the same for any greeter I use. I'm using spectrwm if that matters.

Config & Logs

sudo lightdm --test-mode --debug

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=0 PID=3100
[+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/xdg/lightdm/lightdm.conf.d/90-greeter-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+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: _g_io_module_get_default: Found default implementation local (GLocalVfs) for ?gio-vfs?
[+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 has property CanMultiSession=no
[+0.00s] DEBUG: Seat seat0: Starting
[+0.00s] DEBUG: Seat seat0: Creating greeter session
[+0.00s] DEBUG: Seat seat0: Failed to find session configuration lightdm-slick-greeter 
[+0.00s] DEBUG: Seat seat0: Failed to create greeter session
[+0.00s] DEBUG: Failed to start seat: seat0

/var/log/lightdm/lightdm.log

 Same as above output[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.32.0, UID=0 PID=5247
[+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/xdg/lightdm/lightdm.conf.d/90-greeter-wrapper.conf
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+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: _g_io_module_get_default: Found default implementation local (GLocalVfs) for ‘gio-vfs’
[+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 has property CanMultiSession=no
[+0.00s] DEBUG: Seat seat0: Starting
[+0.00s] DEBUG: Seat seat0: Creating greeter session
[+0.00s] DEBUG: Seat seat0: Failed to find session configuration lightdm-slick-greeter 
[+0.00s] DEBUG: Seat seat0: Failed to create greeter session
[+0.00s] DEBUG: Failed to start seat: seat0

sudo journalctl -b -n -u lightdm.service

 -- No entries --

/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=true
#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 = lightdm-slick-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-session=lightdm-slick-greeter 
#greeter-hide-users=false
#greeter-allow-guest=true
#greeter-show-manual-login=false
#greeter-show-remote-login=true
user-session=spectrwm
#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

ls -1 /usr/share/xgreeters/

lightdm-gtk-greeter.desktop
lightdm-slick-greeter.desktop
web-greeter.desktop

pacman -Qikk lightdm lightdm-slick-greeter

Name            : lightdm
Version         : 1:1.32.0-6
Description     : A lightweight display manager
Architecture    : x86_64
URL             : https://github.com/canonical/lightdm
Licenses        : GPL-3.0-or-later AND (LGPL-2.0-only OR LGPL-3.0-only)
Groups          : None
Provides        : None
Depends On      : glib2  libgcrypt  libx11  libxcb  libxdmcp  libxklavier  pam  polkit  xorg-server  xorg-xmodmap  xorg-xrdb
Optional Deps   : accountsservice: Enhanced user accounts handling [installed]
                  lightdm-gtk-greeter: GTK greeter [installed]
                  xorg-server-xephyr: LightDM test mode [installed]
Required By     : lightdm-gtk-greeter  lightdm-slick-greeter  web-greeter
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 1131.60 KiB
Packager        : Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Build Date      : Sun 11 Feb 2024 01:31:00 PM CST
Install Date    : Wed 23 Jul 2025 11:56:56 AM CDT
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

backup file: lightdm: /etc/lightdm/lightdm.conf (Modification time mismatch)
backup file: lightdm: /etc/lightdm/lightdm.conf (Size mismatch)
backup file: lightdm: /etc/lightdm/lightdm.conf (SHA256 checksum mismatch)
lightdm: 388 total files, 0 altered files
Name            : lightdm-slick-greeter
Version         : 2.0.9-1
Description     : A slick-looking LightDM greeter
Architecture    : x86_64
URL             : https://github.com/linuxmint/slick-greeter
Licenses        : GPL3
Groups          : None
Provides        : None
Depends On      : cairo  freetype2  gtk3  libcanberra  libxext  lightdm  pixman  python  xorg-server  xapp
Optional Deps   : numlockx: enable numerical keypad on supported keyboard
Required By     : None
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 1257.47 KiB
Packager        : Caleb Maclennan <alerque@archlinux.org>
Build Date      : Tue 07 Jan 2025 04:41:06 AM CST
Install Date    : Wed 23 Jul 2025 05:03:31 PM CDT
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

lightdm-slick-greeter: 513 total files, 0 altered files

Last edited by mu40u_n1k4 (2025-07-24 21:57:56)

Scimmia · 2025-07-24 15:34:30

What does `ls -1 /usr/share/xgreeters/` show?

mu40u_n1k4 · 2025-07-24 15:35:45

Scimmia wrote:

What does `ls -1 /usr/share/xgreeters/` show?

lightdm-gtk-greeter.desktop
lightdm-slick-greeter.desktop
web-greeter.desktop

seth · 2025-07-24 20:23:24

pacman -Qikk lightdm lightdm-slick-greeter

mu40u_n1k4 · 2025-07-24 20:26:57

seth wrote:

pacman -Qikk lightdm lightdm-slick-greeter

Name            : lightdm
Version         : 1:1.32.0-6
Description     : A lightweight display manager
Architecture    : x86_64
URL             : https://github.com/canonical/lightdm
Licenses        : GPL-3.0-or-later AND (LGPL-2.0-only OR LGPL-3.0-only)
Groups          : None
Provides        : None
Depends On      : glib2  libgcrypt  libx11  libxcb  libxdmcp  libxklavier  pam  polkit  xorg-server  xorg-xmodmap  xorg-xrdb
Optional Deps   : accountsservice: Enhanced user accounts handling [installed]
                  lightdm-gtk-greeter: GTK greeter [installed]
                  xorg-server-xephyr: LightDM test mode [installed]
Required By     : lightdm-gtk-greeter  lightdm-slick-greeter  web-greeter
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 1131.60 KiB
Packager        : Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Build Date      : Sun 11 Feb 2024 01:31:00 PM CST
Install Date    : Wed 23 Jul 2025 11:56:56 AM CDT
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

backup file: lightdm: /etc/lightdm/lightdm.conf (Modification time mismatch)
backup file: lightdm: /etc/lightdm/lightdm.conf (Size mismatch)
backup file: lightdm: /etc/lightdm/lightdm.conf (SHA256 checksum mismatch)
lightdm: 388 total files, 0 altered files
Name            : lightdm-slick-greeter
Version         : 2.0.9-1
Description     : A slick-looking LightDM greeter
Architecture    : x86_64
URL             : https://github.com/linuxmint/slick-greeter
Licenses        : GPL3
Groups          : None
Provides        : None
Depends On      : cairo  freetype2  gtk3  libcanberra  libxext  lightdm  pixman  python  xorg-server  xapp
Optional Deps   : numlockx: enable numerical keypad on supported keyboard
Required By     : None
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 1257.47 KiB
Packager        : Caleb Maclennan <alerque@archlinux.org>
Build Date      : Tue 07 Jan 2025 04:41:06 AM CST
Install Date    : Wed 23 Jul 2025 05:03:31 PM CDT
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : Signature

lightdm-slick-greeter: 513 total files, 0 altered files

seth · 2025-07-24 21:09:55

Broadsword time…

strace -f -o /tmp/lightdm.strace lightdm --test-mode --debug

nb. you cannot sudo strace, you'll either have to run this as unprivileged user or from a root shell.

mu40u_n1k4 · 2025-07-24 21:19:04

seth wrote:

Broadsword time…
strace -f -o /tmp/lightdm.strace lightdm --test-mode --debug
nb. you cannot sudo strace, you'll either have to run this as unprivileged user or from a root shell.

Looking at the output from that I seen something odd...

10855 openat(AT_FDCWD, "/usr/local/share/lightdm/greeters/lightdm-slick-greeter .desktop", O_RDONLY|O_CLOEXEC <unfinished ...>
10860 clock_gettime(CLOCK_MONOTONIC,  <unfinished ...>
10855 <... openat resumed>)             = -1 ENOENT (No such file or directory)
10860 <... clock_gettime resumed>{tv_sec=8073, tv_nsec=138484016}) = 0
10855 openat(AT_FDCWD, "/usr/share/lightdm/greeters/lightdm-slick-greeter .desktop", O_RDONLY|O_CLOEXEC <unfinished ...>
10860 ppoll([{fd=8, events=POLLIN}, {fd=9, events=POLLIN}, {fd=10, events=POLLIN}], 3, NULL, NULL, 8 <unfinished ...>
10855 <... openat resumed>)             = -1 ENOENT (No such file or directory)
10855 openat(AT_FDCWD, "/usr/local/share/xgreeters/lightdm-slick-greeter .desktop", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
10855 openat(AT_FDCWD, "/usr/share/xgreeters/lightdm-slick-greeter .desktop", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)

There was a damn space at the end of my config line, since it wasn't trimmed or anything it was looking for lightdm-slick-greeter .desktop with a space. Spent way to long just to figure that out.

Thanks a ton!

seth · 2025-07-24 21:49:27

The broadsword is messy but usually gets the job done
Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

Arch Linux

#1 2025-07-24 15:28:56