I was looking for a way to switch to gdm3 from lightdm, when I found this answer. So I tried to apply it, and entered sudo dpkg-reconfigure gdm3, then a selection screen appeared with 2 options: gdm3 and lightdm. It was the same screen that appeared during the installation of GNOME (using sudo apt install ubuntu-gnome-desktop && gnome-shell). I chose gdm3 then pressed Enter, then I got this error:

gdm.service is not active, cannot reload.
invoke-rc.d: initscript gdm3, action "reload" failed.

Any ideas?


It turns out that it just required a reboot to work. But I still want to know the meaning of that error I got. Does anyone have any explanation?


re: sudo dpkg-reconfigure gdm3 error message.

Just reboot and you should be running gdm3.

The error that you're receiving just means that gdm3 wasn't already running, so it couldn't reload it.

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  • do you know what that error means though? – Tooniis Jul 24 '17 at 20:04
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    It just means that gdm3 wasn't already running, so it couldn't reload it. Kind of a bogus error. – heynnema Jul 24 '17 at 20:05
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    this didn't work for me – trust_words Dec 29 '18 at 19:16
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    @trust_words please start a new question and we'll try and help you. – heynnema Dec 29 '18 at 20:46

Use this sudo dpkg-reconfigure lightdm in place of sudo dpkg-reconfigure gdm3 this and then choose gdm3.

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    Can you please explain how would that make any difference? When either of them is used, options are shown to switch default DM. – Kulfy Jun 24 '19 at 19:14
  • But there is something different between both of them as I tried it work, When I work on lightdm I use dpkg-reconfigure lightdm and on gdm use gdm in place of lightdm and it works without any error – Danraptor Jul 3 '19 at 8:38
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    I agree, you should specify the one you are using at the moment. Don't know why but it's always worked for me. – Organic Marble Mar 12 at 23:32

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