lightdm does not work on eoan on raspberry pi 4

[Kenneth Zadeck]

if you follow the directions on https://wiki.ubuntu.com/ARM/RaspberryPi

sudo apt-get install xubuntu-desktop

about 20% thru the installation it will ask which window manager you want (using dpkg-reconfigure).
if you select lightdm, you will only get a blank greeter screen after you reboot.

using sudo dpkg-reconfigure gdm3

resets this to gdm3 and after a reboot, everything is fine.

this was done on a clean armhf eoan install on a 4gb raspberry pi 4B.

I have done the install several times. This bug is repeatable.

[Kenneth Zadeck (zadeck)]

change the term "blank screen" to "unresponsive blank screen" in the above. Sorry

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Razor_alpha (razoralpha)]

The very same happened to me on 19.10 aarch64 version on my Pi 4 4GB, changing to gdm3 did result in a usable system for me too.

[Sebastien Bacher (seb128)]

Could you get the 'journalctl -b 0' log from a failed session?

[Kenneth Zadeck (zadeck)]

it is nice to know that i am not the only one wrestling with these alligators.
here is your log as requested.

kenny

[Kenneth Zadeck (zadeck)]

Last week provided the log file as requested. is it possible to get this bug moved off the incomplete list?

[Kenneth Zadeck (zadeck)]

Just for the record, I tried to change the memory size to 2gb and it did not help. There are other open raspberry pi 4 bugs that are dependent on having more that 3gb or ram and so i decided to test that possibility (see https://bugs.launchpad.net/ubuntu/+source/linux-raspi2/+bug/1848703) especially since the other person who sees this bug also has a 4gb system. However it does not seem to help.

[Kenneth Zadeck (zadeck)]

I found the following page online
https://bluesabre.org/2019/10/20/install-xubuntu-19-10-on-a-raspberry-pi-4/

the claim is that this bug is in the greeter and it has been fixed upstream.
i followed the directions to install a different greeter and the xubuntu now works.

i had updated to the latest kernel (1014) before trying this fix but it did not help.

The blog did not give a pointer to the upstream fix but it sounds like you are a pull away from fixing this.

Kenny

[Balint Reczey (rbalint)]

The bug can still be observed on 20.04 with Raspberry Pi 2 Model B Rev 1.1. Switching to slick-greeter still fixes lightdm.

[Roman (thezub)]

Not only is this bug still present on 20.0 with a Pi 3B+ but switching to Slick greeter doesn't help at all. XDM works fine, etc. but Slick Greeter is still based on LightDM which is where the issue appears to be, not just with the particular GTK greeter.

[Sebastien Bacher (seb128)]

Those still having the issue on focal, which greeter are you using? It could be the same issue than https://launchpad.net/ubuntu/+source/lightdm-gtk-greeter/2.0.6-0ubuntu2 ?

[Roman (thezub)]

Using the GTK greeter and also tried Slick greeter, both show nothing - a blank screen - and I would have to ctrl alt f1, get to a terminal screen, put in a username and password there and then "startx" but the f7 or wherever the lightdm goes, that does not work when switching to it.

[Sebastien Bacher (seb128)]

Could you switch to a vt after getting the issue and do 'journalctl -b 0 > journal' and add the journal file to the bug?

[Launchpad Janitor (janitor)]

[Expired for lightdm (Ubuntu) because there has been no activity for 60 days.]

[Kippykip (kippykip)]

Still appears to be here, although it works on arm64?
Basically I tested Ubuntu Server 20.04 for the RPi 400, on arm64 (64-bit) typing in "sudo apt install xubuntu-desktop" has a distro that works perfectly fine.

However on Ubuntu Server 20.04 for armhf (32-bit), doing the same "sudo apt install xubuntu-desktop" I get the same black screen thing you guys are talking about.
Makes sense as xubuntu uses lightdm by default.

Although installing slick-greeter also worked around the issue for me.