GDM error on ec2 instance with DCV

Support & Help Requests
1

Hello,

I have set up an ec2 instance with ubuntu 24.04 and then installed ubuntu-mate-desktop and set up DCV. I can log in through DCV but then the display just stales at the loading animation.
Running
journalctl -b -u gdm shows the lines

Gdm: GdmDisplayStore: Adding display /org/gnome/DisplayManager/Displays/97236947544576 to store
Gdm: on_display_added: assertion 'GDM_IS_REMOTE_DISPLAY (display)' failed

and

Gdm: on_display_removed: assertion 'GDM_IS_REMOTE_DISPLAY (display)' failed
**Gdm: Child process -1155 was already dead.**

Any idea what is failing?

cat /etc/X11/default-display-manager
/usr/sbin/gdm3

BTW: I was able to get it to work with ubuntu-desktopinstead of mate

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2

Hi, @diophantus7 and welcome to the Ubuntu MATE Community!

3

It might be the fact that Ubuntu uses the Wayland protocol for displaying a desktop while Ubuntu-MATE uses the X11 protocol which is completely different.
I guess DCV is oblivious to the fact that it now has to talk the X11 protocol on a Ubuntu VM besides the fact that i don't even know if it is able to support X11 at all.

OTOH, I might be completely mistaken because I have no Idea how DCV connects to the graphical server ( also I've never even heard of DCV before).

2 Likes
4

There's also the possibility that GDM and MATE aren't playing nicely together in this use-case. You could try switching to lightdm.

You should also look for support directly from the developers (or other users) of EC2 and DCV.

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5

I do have Wayland disabled in /etc/gdm/custom.conf. That is also suggested by AWS for the gnome desktop.

That's what I was thinking too. On the other hand I have been using GDM with MATE. But from what I remember that is on ubuntu 22.04 or even 20.04.

Also I can add, that when I set everything up with Gnome (working) and then install ubuntu-mate-desktop, I cannot go back to Gnome. The login stays at the loading indicator as it does with MATE. Not sure if that helps anyhow.

6

Yeah, some files and settings don't get reverted when a desktop (package) is removed. I'm not an expert in switching between desktops because I avoid it like the plague. Others around here can hopefully chime in.

1 Like