Installing – and Uninstalling – LightDM in Linux Mint 18.2

Clement Lefebvre’s blog entry on how to upgrade Linux Mint to Version 18.2 (Sonya) indicates that the new LightDM display manager, along with the “Slick” greeter, is not installed by default. However, a section of the blog shows how to switch from MDM to LightDM.

Having updated my installation to Sonya, I decided to give LightDM a try. Essentially this involves using the command: apt install slick-greeter lightdm-settings. However, rebooting the computer produced the error message “Failed to start the X server”.

Ignoring this error resulted in the new login screen being displayed. The writeup on the Mint web site of Sonya’s new features asserted that the Slick greeter: “…provides the computer with a beautiful login screen…” Regrettably, in my view, the login screen isn’t particularly pretty. So, given this, and the evident need to troubleshoot the failure to start the Xserver, I decided to revert back to MDM.

This was easily done using the command:

sudo dpkg-reconfigure mdm

To clean things up, I also uninstalled LightDM using the command:

sudo apt-get purge lightdm


How to upgrade to Linux Mint 18.2

New features in Linux Mint 18.2 MATE

How To Install LightDM In Linux Mint (And Replace MDM)

How to uninstall lightdm?

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6 Responses to Installing – and Uninstalling – LightDM in Linux Mint 18.2

  1. The error message “Failed to start the X server” in my case appears to be from having both LightDM and MDM installed at the same time and not from a problem with LightDM. If you want to run LightDM the default configuration changes do lead to LightDM starting but MDM tries to start later and can’t when LightDM is already acting as the X server.

    I have successfully installed LightDM and switched to it on multiple machines but on my main laptop I can’t get LightDM to start and when I remove MDM I get no X server.

    With what Linux Mint 18.2 is delivering today I can run MDM when both MDM and LightDM are installed but when I run LightDM with MDM also installed I get the “Failed to start the X server” error but in fact it is really an X server is already running error until I remove LightDM or switch back to MDM.

    • Alan German says:


      Thank you for this information. It may well be of assistance to others. For my part, I didn’t really like the look of LightDM and so I was happy to revert to MDM.


      • Rebel450 says:

        Hi Alan,
        I agree with you in full:
        Here Ci 18.3 clean install = a lot of issues with many apps and appearance settings;
        even after several new installations.
        On another machine I’d install Ci 18.1, then upgraded to 18.2 AND on dialog screen
        MDM instead of LDM chosen = running perfect with everything (still Kernel 4.4.0-116)
        a longer time (several months with daily use) meanwhile.
        Now I will try to revert to MDM on Ci 18.3 – let’s see…..
        Kind Regards

        And yes, LDM looks cheap, simple, and ugly with an yesterdays appearance; crap (period) 😉

  2. Rigel O'Rion says:

    Thanks for post,
    and Yes, I also have found LightDM to be quite a let down, compared to the more feature-full, slicker, and more responsive MDM.

    …and regarding Lawrence A. Murakami ‘s post, -you can have both mdm and lightdm pkgs installed, but you’ll need to edit /etc/X11/default-display-manager and replace lightdm with mdm. You may get some annoying “failed…” messages in console during boot with lightdm complaining it can’t start, but your X will come up, at least mine did.
    But in either case, it’s best to “purge” one or the other, as mentioned by the OP, just to clean things up.

  3. asd says:

    how do i add mdm themes?

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