lightdm does not start

[G.M.]

Hi,

Under XUbuntu 20.04.

dist-upgraded my install yesterday. Since then, computer infinite loops on boot with message: "A start job is running for Hold until boot process finishes up"

Thanks to:
https://bugs.launchpad.net/ubuntu/+source/plymouth/+bug/1871641

I managed to get rid of the infinite loop

However, I now face a console login screen.

I tried to run lightdm manually (`/etc/init.d/lightdm start`). It does not start with no error meaningful to me.

In the other hand, lxdm and gdm3 start with no problem.

Then, I remembered I used lightdm-gtk-greeter-settings (v1.2.2-3) a few days ago and did not reboot my computer since then.

Thinking it might be a configuration pb, I purged lightdm and re-installed it. But same problem.

Any help appreciated. Running lxdm in the meantime...

```
# /etc/init.d/lightdm start
Starting lightdm (via systemctl): lightdm.serviceJob for lightdm.service failed because the control process exited with error code.
See "systemctl status lightdm.service" and "journalctl -xe" for details.
 failed!
```

```
# systemctl status lightdm.service
● lightdm.service - Light Display Manager
     Loaded: loaded (/lib/systemd/system/lightdm.service; indirect; vendor preset: enabled)
     Active: failed (Result: exit-code) since Wed 2020-06-10 16:52:29 CEST; 46s ago
       Docs: man:lightdm(1)
    Process: 10618 ExecStartPre=/bin/sh -c [ "$(basename $(cat /etc/X11/default-display-manager 2>/dev/null))" = "lightdm" ] (code=exited, status=0/SUCCESS)
    Process: 10621 ExecStart=/usr/sbin/lightdm (code=exited, status=1/FAILURE)
   Main PID: 10621 (code=exited, status=1/FAILURE)

juin 10 16:52:29 BAL157X-og systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 5.
juin 10 16:52:29 BAL157X-og systemd[1]: Stopped Light Display Manager.
juin 10 16:52:29 BAL157X-og systemd[1]: lightdm.service: Start request repeated too quickly.
juin 10 16:52:29 BAL157X-og systemd[1]: lightdm.service: Failed with result 'exit-code'.
juin 10 16:52:29 BAL157X-og systemd[1]: Failed to start Light Display Manager.
```

```# journalctl -xe``` output attached.