LightDM is a cross-desktop display manager. A display manager is a daemon that:

  • Runs display servers (e.g. X) where necessary.
  • Runs greeters to allow users to pick which user account and session type to use.
  • Allows greeters to perform authentication using PAM.
  • Runs session processes once authentication is complete.
  • Provides remote graphical login options.

Key features of LightDM are:

  • Cross-desktop – supports different desktop technologies.
  • Supports different display technologies (X, Mir, Wayland …).
  • Lightweight – low memory usage and fast performance.
  • Guest sessions.
  • Supports remote login (incoming – XDMCP, VNC, outgoing – XDMCP, pluggable).
  • Comprehensive test suite.


Setup LightDM to work nicely on Multidisplay systems

Use Arandr to fix display setup on multi-display for LightDM

For EndeavourOS (and other Archlinux based):

  1. Install arandr from repositories: sudo pacman -S arandr
  2. setup displays with arandr.
  3. save the setup as monitor in the given directory.
  4. copy the saved script to lightdm directory:
    sudo cp ~/.screenlayout/ /etc/lightdm/
  5. make it executable:
    sudo chmod +x /etc/lightdm/
  6. edit lightdm.conf:
    sudo nano /etc/lightdm/lightdm.conf
    uncomment the display setup option and add the path to the script:
    (you can also add this line at the end of the file)
    save the file [Ctrl+X]
  7. restart lightdm to see if it is working:
    sudo systemctl restart lightdm


  1. Lightdm fails to start at all (black screen with no login GUI showing up)

lightdm have an issue where it happens that it starts faster than X is ready, or the GPU driver is not fully loaded, one solution is to set logind-check-graphical=true inside lightdm.conf

uncomment the line #set logind-check-graphical=false and change from false to true like so:

set logind-check-graphical=true

There are several different cases where Lightdm can fail to start, mostly it is the case if GPU driver is not loading at all or to late. what makes X system fail to be available for lightdm.

It can be also typo or wrong setting in the config file/s, as EndeavourOS using lightdm-gtk-greeter per default it can be missing one of the needed packages ( lightdm lightdm-gtk-settings lightdm-gtk-greeter) causing it failing to start.

Lightdm has also build-in debugging mode you can start from CLI if it fails:

lightdm --test-mode --debug

You can also run this from terminal if X is running.

May you need to install Xephyr:

sudo pacman -S xorg-server-xephyr

will give a debugging log like this:

Going to the debugging output you can find the culprit of what may cause the issue for you.

As the status mostly do not give helpful output:

systemctl status lightdm

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