Why can't I change my display manager? (GDM to LightDM)

edit

Check if it is disabled:

$ sudo systemctl status {lightdm,gdm}.service

Next, mask gdm if it is "enabled":

$ sudo systemctl mask gdm.service

Or, if you don't even want gdm (or possibly GNOME), try

$ yum remove gdm

Warning: That might remove GNOME applications (Nautilus, stuff like that), so watch out for that.

Then, enable LightDM

$ sudo systemctl enable lightdm.service

HTH.

The man page for system-switch-displaymanager doesn't mention lightdm, but I tried it anyway.

If you give the argument:

$ system-switch-displaymanager lightdm

First you get the same error output as when you use systemctl:

Failed to issue method call: Operation not supported

Then you get a line of output (can't remember it exactly) from system-switch-displaymanager that says the operation was a success.

However, when I reboot, I have NO display manager. I log in and am at a bash prompt. So I then used system-switch-displaymanager to switch back to GDM:

$ system-switch-displaymanager gdm

There is still no way to successfully switch from GDM to LightDM.

I often change DM with following step:

1. Enter console mode by press Ctrl-Alt-F3 (F2~F8 is also good), and login. Do NOT try to change display manager in GUI, as the behavior is unpredictable.
2. sudo systemctl disable gdm
3. sudo systemctl enable lightdm
4. Stop gdm with sudo systemctl stop gdm
5. Start lightdm with sudo systemctl start lightdm

That's it.

I just successfully switched my display manager from LightDM to GDM with advice from this Fedora Users mailing list post.

First of all, make sure the GDM manager you wish to use is installed on your system.

I started with an Xfce system, and the Xfce spin uses LightDM. When I later installed GNOME, it brought GDM along with it.

But if you want to switch to GDM without GNOME, install it:

$ sudo yum install gdm

Then you switch one off and the other on:

$ sudo systemctl disable lightdm.service
$ sudo systemctl enable gdm.service

Then reboot your system, and the new display manager will come up.

The problem is going back.

I can sucessfully do this:

$ sudo systemctl disable gdm.service

But this command doesn't work:

$ sudo systemctl enable lightdm.service

I get this output in the terminal:

Failed to issue method call: Operation not supported

Any ideas?

I never tinkered with systemctl. I simply used the https://apps.fedoraproject.org/packages/system-switch-displaymanager package and it worked just fine. Give it a go?