What is the difference between GDM and LightDM? How can one switch between them. I mean if I have selected LightDM during installation process, will I be able switch to GDM?

1 Answer 1


Both LightDM and GDM (GNOME Display Manager) are login managers.
They both provide graphical login capabilities (the GUI with the list of the system's users) as well as remote logins using the XDMCP protocol.

Ubuntu is supposed to officially replace GDM in favor of the lighter and more easily customizable LightDM

You can have both of them installed (or add even more, like KDM), but only one will be used at any time.

The default can be selected by running:

sudo dpkg-reconfigure gdm (if gdm is already installed)

More information on LightDM can be found on the Ubuntu wiki.

  • 34
    they are not desktop managers: gnome, kde and unity are. GDM and LightDM are called login managers or display managers
    – josinalvo
    Aug 15, 2012 at 14:28
  • 3
    sudo dpkg-reconfigure gdm3 worked for me.
    – Mooncrater
    Apr 25, 2019 at 9:48
  • So there is a bug for this reported: bugs.launchpad.net/bugs/1874194
    – eddy147
    Jun 12, 2020 at 16:06

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