Had to do a reboot due to some sound issues today. After reboot system does not do normal login. It starts a screen keyboard. I can login ok but lightdm is missing.
I had an app that configured lightdm greeter in applications menu. That is gone. I did a reinstall but no changes. mate desktop using lightdm for 10 years probably.
There is a message below about bus name for display manager.
Under systemd, LightDM is managed as a system service, so it gets started and supervised by the init system during boot rather than just being launched as a standalone application.
That’s why checking sudo systemctl status lightdm is usually the best first step.
Got it fixed with assistance from AI search. Gave info below:
Run sudo update-alternatives --config default-displaymanager to select from installed managers (e.g., SDDM, LightDM,)
Did the above and lightdm was not selected. I think sddm was. Have no idea how anything related to that setting was changed but set default to lightdm and rebooted and all was fine.
Still have not recovered light-greeter tweak app.
The update-alternatives framework is old, but if you have an old installation upgraded across multiple releases that explains why you may still be using it instead. I rely solely on modern SDDM (Wayland), and have the sddm.service explicitly enabled. The same can be done for LightDM.
So where do you set display manager to SDDM? I’ll look to see if that exists on my system. My system is a long evolved system. I use x11 as my mate de is apparently not fully functional on wayland. But I am not a gamer.
Several files the AI suggested looking at did not exist. It is often wrong but worth a look.
I look at my /etc/sysconfig/displaymanager and there is no line in it with something like:
DISPLAYMANAGER=“lightdm” or anything else.
Should I add a line.
## Path: Desktop/Display manager
## Description: settings to generate a proper displaymanager config
## Type: yesno
## Default: no
#
# Allow remote access (XDMCP) to your display manager (xdm/kdm/gdm). Please note
# that a modified kdm or xdm configuration, e.g. by KDE control center
# will not be changed. For gdm, values will be updated after change.
# XDMCP service should run only on trusted networks and you have to disable
# firewall for interfaces, where you want to provide this service.
#
DISPLAYMANAGER_REMOTE_ACCESS="no"
## Type: yesno
## Default: no
#
# Allow remote access of the user root to your display manager. Note
# that root can never login if DISPLAYMANAGER_SHUTDOWN is "auto" and
# System/Security/Permissions/PERMISSION_SECURITY is "paranoid"
#
DISPLAYMANAGER_ROOT_LOGIN_REMOTE="no"
## Type: yesno
## Default: yes
#
# Let the displaymanager start a local Xserver.
# Set to "no" for remote-access only.
# Set to "no" on architectures without any Xserver (e.g. s390/s390x).
#
DISPLAYMANAGER_STARTS_XSERVER="yes"
## Type: yesno
## Default: no
#
# TCP port 6000 of Xserver. When set to "no" (default) Xserver is
# started with "-nolisten tcp". Only set this to "yes" if you really
# need to. Remote X service should run only on trusted networks and
# you have to disable firewall for interfaces, where you want to
# provide this service. Use ssh X11 port forwarding whenever possible.
#
DISPLAYMANAGER_XSERVER_TCP_PORT_6000_OPEN="no"
## Type: string
## Default:
#
# Define the user whom should get logged in without request. If string
# is empty, display standard login dialog.
#
DISPLAYMANAGER_AUTOLOGIN=""
## Type: yesno
## Default: no
#
# Allow all users to login without password, but ask for the user, if
# DISPLAYMANAGER_AUTOLOGIN is empty.
#
DISPLAYMANAGER_PASSWORD_LESS_LOGIN="no"
## Type: yesno
## Default: no
#
# Display a combobox for Active Directory domains.
#
DISPLAYMANAGER_AD_INTEGRATION="no"
## Path: Desktop/Display manager
## Type: string(Xorg)
## Default: "Xorg"
#
DISPLAYMANAGER_XSERVER="Xorg"
(base) tom@mydesktop: ~ $ sudo systemctl status display-manager
● display-manager-legacy.service - X Display Manager
Loaded: loaded (/usr/lib/systemd/system/display-manager-legacy.service; enabled; preset: enabled)
Active: active (running) since Thu 2026-05-28 19:28:50 CDT; 1h 18min ago
Invocation: 708232cdf36743cfa56f3044255f376c
Process: 2048 ExecStart=/usr/lib/X11/display-manager start (code=exited, status=0/SUCCESS)
Main PID: 2152 (lightdm)
Tasks: 6 (limit: 38215)
CPU: 5min 29.116s
CGroup: /system.slice/display-manager-legacy.service
├─2152 /usr/sbin/lightdm
└─2160 /usr/bin/Xorg.bin :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
May 28 19:28:49 mydesktop display-manager[2144]: XKBLAYOUT: us
May 28 19:28:49 mydesktop display-manager[2144]: XKBLAYOUT is already set. Better don't touch X11 keyboard configuration.
May 28 19:28:50 mydesktop systemd[1]: Started X Display Manager.
May 28 19:28:55 mydesktop display-manager[2048]: Starting service lightdm
May 28 19:28:55 mydesktop display-manager[2326]: /usr/bin/xrdb: No such file or directory
May 28 19:28:55 mydesktop display-manager[2326]: /usr/bin/xrdb: can't open file '/Xresources'
May 28 19:29:19 mydesktop lightdm[2710]: gkr-pam: unable to locate daemon control file
May 28 19:29:19 mydesktop lightdm[2710]: gkr-pam: stashed password to try later in open session
May 28 19:29:19 mydesktop lightdm[2710]: pam_unix(lightdm:session): session opened for user tom(uid=1000) by tom(uid=0)
May 28 19:29:19 mydesktop lightdm[2710]: gkr-pam: gnome-keyring-daemon started properly and unlocked keyring
(base) tom@mydesktop: ~ $ `Preformatted text`
