TigerVNC server not working after do_release_upgrade to 22.04.4 LTS

[Bo Berglund]

On Thu, 21 Mar 2024 10:07:56 +0100, Bo Berglund <bo.berglund at gmail.com> wrote:

>On Wed, 20 Mar 2024 20:35:00 -0400, Sam Varshavchik <mrsam at courier-mta.com>
>wrote:
>
>>Bo Berglund writes:
>>
>>> After the upgrade/reboot I can no longer access the VNC functionality!
>>> The client  (RealVNC-Viewer on Windows 10) just hangs and never connects, so  
>>> I
>>> checked the laptop status:
>>> ---------------------
>>> sudo systemctl status vncserver at 1
>>
>>Did 22.04 install this systemd service for vncserver? I don't have this in  
>>20.04, I just run vncserver manually.
>
>The service was installed back in the 20.04 version and was transfered in the
>dist-upgrade I did yesterday.
>It tries to run but the vncserver exits with an error early on as can be seen in
>the journal.
>My problem is to understand why it fails and remedy it...
>
>>Are you also logged in on the console, by any chance. If so try logging off  
>>the console before attempting a VNC connection. Fedora has a known  
>>limitation with being unable to support both a console session and a VNC  
>>session for the same user at the same time, with its systemd-launched  
>>vncserver.
>
>The laptop is running headless (no attached monitor) and the lid closed, so
>there is no hardware screen attached.
>The VNC service is set to use screen #1 rather than #0, and that virtual screen
>is suppopsed to be created by running vncserver with the argument 1 for the
>screen.
>
>I am only connected to the laptop using PuTTY (SSH connection) so I am on a
>terminal but only via SSH, so not the "real" terminal...
>And I am not running Fedora, this is Ubuntu 20.04 using Cinnamon upgraded to
>22.04.
>
>What happened in the upgrade I don't know, something not good for VNC seems to
>have occurred.

Trying asking here again....

It seems like the VNC servers available work differently depending on the actual
desktop manager configured for the system. The TigerVNC I installed previously
worked fine on 20.04 but not on 22.04

So now I suspect the release-upgrade changed the desktop manager thus breaking
VNC.

What I wrote above regarding what the system is running is not fully correct
since I do not know for sure that the 20.04 ran Cinnamon, it might be something
else entirely...

But I have a problem even knowing which desktop environment is installed and
running by default...

When I google this I mostly find advice that is geared towards commands issued
*inside* the desktop environment and that is something I cannot do since the
system is headless and I can no longer reach the GUI screen via VNC...

Some kind of hen-and-egg problem here....

The latest suggestion I found was to interrogate systemd and I did so with the
following result (lines are wrapped by my newsreader editor):

$ systemctl status display-manager.service
? lightdm.service - Light Display Manager
     Loaded: loaded (/lib/systemd/system/lightdm.service; indirect; vendor
preset: enabled)
     Active: active (running) since Wed 2024-03-20 09:26:00 CET; 4 days ago
       Docs: man:lightdm(1)
    Process: 1733 ExecStartPre=/bin/sh -c [ "$(basename $(cat
/etc/X11/default-display-manager 2>/dev/null))" = "lightdm" ] (code=exited,
status=0/SUCCESS)
   Main PID: 1736 (lightdm)
      Tasks: 7 (limit: 18991)
     Memory: 51.7M
        CPU: 18.893s
     CGroup: /system.slice/lightdm.service
             +-1736 /usr/sbin/lightdm
             +-1743 /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth
/var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
             +-1966 lightdm --session-child 13 20

mar 20 09:26:00 auriga-ubuntu systemd[1]: Starting Light Display Manager...
mar 20 09:26:00 auriga-ubuntu lightdm[1736]: Seat type 'xlocal' is deprecated,
use 'type=local' instead
mar 20 09:26:00 auriga-ubuntu systemd[1]: Started Light Display Manager.
mar 20 09:26:02 auriga-ubuntu lightdm[1770]: pam_unix(lightdm-greeter:session):
session opened for user lightdm(uid=122) by (uid=0)
mar 20 09:26:02 auriga-ubuntu lightdm[1770]: gkr-pam: gnome-keyring-daemon
started properly
mar 20 09:26:05 auriga-ubuntu lightdm[1966]: pam_succeed_if(lightdm:auth):
requirement "user ingroup nopasswdlogin" not met by user "bosse"


Is there someone here who can decode this into a reason for the TigerVNC server
not successfully running?



-- 
Bo Berglund
Developer in Sweden