Black window on Ubuntu 22.04

[Felix Natter]

hello TurboVNC Users,

I have client and server using up-to-date Ubuntu 22.04.x VMs
(I tried both=turbovnc-3.0.3 and both=turbovnc-3.1).

Of course I am using XDG_SESSION_TYPE=x11.

I can start :1, but when I try to connect with the vncviewer,
I get a blank/black turbovnc window.

I could not see anything unusual in the (server-)log.
I tried with "export TVNC_WM=2d" (before starting :1).
I read this:

https://turbovnc.org/Documentation/Compatibility30

What am I doing wrong?

Many Thanks and Best Regards,
Felix

[DRC]

Is GNOME installed on the machine? You don’t have to use GNOME, but it is the default window manager (and -wm 2d invokes gnome-classic), so if you don’t want to use it, you will need to specify a different window manager.

On Nov 18, 2023, at 3:19 PM, 'Felix Natter' via TurboVNC User Discussion/Support <turbovn...@googlegroups.com> wrote:

hello TurboVNC Users,

--
You received this message because you are subscribed to the Google Groups "TurboVNC User Discussion/Support" group.
To unsubscribe from this group and stop receiving emails from it, send an email to turbovnc-user...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/turbovnc-users/859c1063-2554-4f57-9b44-aeabf5372222n%40googlegroups.com.

[Felix Natter]

DRC schrieb am Samstag, 18. November 2023 um 23:58:18 UTC+1:

Is GNOME installed on the machine? You don’t have to use GNOME, but it is the default window manager (and -wm 2d invokes gnome-classic), so if you don’t want to use it, you will need to specify a different window manager.

hello DRC,

thank you for your answer. Yes, I can locally log on to GNOME4, but I guess it's Ubuntu modified version (since the same test works fine on Debian12).

But I indeed I didn't have "GNOME2" installed on the VM(s): I now installed gnome-session-flashback and get the same black screen/window as with GNOME4.

Any idea anyone? Since Ubuntu22.04/GNOME42 is officially supported [1]?

[1] https://turbovnc.org/Documentation/Compatibility30

Could I use tigervnc with virtualgl if I cannot solve this?

[DRC]

There is no GNOME 2 on modern Linux distros. (GNOME 2 is actually MATE.) The GNOME flashback session is merely GNOME 4 with a UI that behaves more like GNOME 2, but those differences are purely cosmetic. TurboVNC is supposed to use the regular GNOME session by default and the flashback session if you specify “2d” as the window manager. Can you post the TurboVNC session log (under ~/.vnc on the host)? That may give me a clue as to what is failing. It may be that we assume that a particular package is installed that isn’t installed on your system, which may mean that our DEB config needs to be altered to specify that package.

On Nov 19, 2023, at 10:24 AM, 'Felix Natter' via TurboVNC User Discussion/Support <turbovn...@googlegroups.com> wrote:



--

You received this message because you are subscribed to the Google Groups "TurboVNC User Discussion/Support" group.
To unsubscribe from this group and stop receiving emails from it, send an email to turbovnc-user...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/turbovnc-users/70fb9320-e152-4713-aac9-55410aca1e5bn%40googlegroups.com.

[Felix Natter]

DRC schrieb am Sonntag, 19. November 2023 um 17:21:09 UTC+1:

There is no GNOME 2 on modern Linux distros. (GNOME 2 is actually MATE.) The GNOME flashback session is merely GNOME 4 with a UI that behaves more like GNOME 2, but those differences are purely cosmetic. TurboVNC is supposed to use the regular GNOME session by default and the flashback session if you specify “2d” as the window manager. Can you post the TurboVNC session log (under ~/.vnc on the host)? That may give me a clue as to what is failing. It may be that we assume that a particular package is installed that isn’t installed on your system, which may mean that our DEB config needs to be altered to specify that package.

hello DRC,

Log is attached, thanks! Do I need to enable debug logging?

BTW: it seems that tigervnc server/client fails with a similar issue.

Many Thanks and Best Regards!

Felix

[Felix Natter]

hello DRC,

the first problem was that by default, GDM3 is running with wayland. If I set waylandEnable=false in [daemon] section
of /etc/gdm3/custom.conf and reboot (systemctl restart gdm3 is not enough), then I can at least

create and connect to a localhost server :) Do you want to document this in the 3.0 compatibility section?

Regarding VNC between the two VMs - these may be permission issues as I don't have LDAP (just local users)
in these two (test-)VMs. I will investigate.

When I try to start gnome-terminal in the (localhost-)VNC Session, I get:

# Error creating terminal: Object does not exist at path "/org/gnome/Terminal/Factory0"

BUT this seems to be because of the localhost session [1]

[1] https://github.com/TigerVNC/tigervnc/issues/407

[Felix Natter]

Felix Natter schrieb am Montag, 20. November 2023 um 19:29:11 UTC+1:

hello DRC,

the first problem was that by default, GDM3 is running with wayland. If I set waylandEnable=false in [daemon] section
of /etc/gdm3/custom.conf and reboot (systemctl restart gdm3 is not enough), then I can at least

create and connect to a localhost server :) Do you want to document this in the 3.0 compatibility section?

 Ok, I tried to enable wayland for gdm3 and it still works (after reboot), so I am not sure that this was the fix.

I will try with a fresh Ubuntu 22.04 on the weekend.

Thanks for the patience,

Felix

[DRC]

On 11/20/23 1:29 PM, 'Felix Natter' via TurboVNC User Discussion/Support
wrote:

> the first problem was that by default, GDM3 is running with wayland.
> If I set waylandEnable=false in [daemon] section
> of /etc/gdm3/custom.conf and reboot (systemctl restart gdm3 is not
> enough), then I can at least
> create and connect to a localhost server :) Do you want to document
> this in the 3.0 compatibility section?

TurboVNC should have no dependency on GDM unless you are trying to run
the window manager with VirtualGL.  If you are trying to run the window
manager with VirtualGL (and the traditional GLX back end, as opposed to
the newer but less compatible EGL back end), then yes, the need to
disable Wayland in GDM is a known issue that vglserver_config handles
automatically when you configure the system as a VGL host.  However, GDM
is irrelevant to TurboVNC otherwise.  I just tested TurboVNC 3.1 on an
Ubuntu 22.04 virtual machine, and the default configuration of TurboVNC
starts GNOME with no issues.

> Regarding VNC between the two VMs - these may be permission issues as
> I don't have LDAP (just local users)
> in these two (test-)VMs. I will investigate.
>
> When I try to start gnome-terminal in the (localhost-)VNC Session, I get:
> # Error creating terminal: Object does not exist at path
> "/org/gnome/Terminal/Factory0"
> BUT this seems to be because of the localhost session [1]
> [1] https://github.com/TigerVNC/tigervnc/issues/407

That is a limitation of TigerVNC, but TurboVNC should allow multiple
GNOME instances, including a simultaneous local and remote instance. 
Before I officially list a window manager on this page:
https://turbovnc.org/Documentation/Compatibility30, I always test
whether I can successfully use one instance of it in a TurboVNC session
simultaneously with another instance of it running with VGL in a
TurboVNC session simultaneously with another instance of it running locally.

However, your inability to launch multiple simultaneous sessions gave me
a clue, and I noticed in your TurboVNC Server log that xstartup.turbovnc
isn't creating a new D-Bus instance for the TurboVNC session.  Can you
confirm whether /usr/bin/dbus-launch is installed on your system?  If
not, install the dbus-x11 package. If that is the issue, then I need to
modify our .deb so that it automatically requests installation of dbus-x11.

[DRC]

Please let me know if installing the dbus-x11 package fixed the issue.

[DRC]

Note that Ubuntu 22.04 was the first Ubuntu LTS release in which
gnome-session-bin did not depend on dbus-x11, so it is plausible that
your system did not have dbus-x11 installed.  I have updated the
TurboVNC .deb manifest so that it now requires dbus-x11.

[Felix Natter]

hello DRC,

DRC schrieb am Dienstag, 21. November 2023 um 18:55:03 UTC+1:

Note that Ubuntu 22.04 was the first Ubuntu LTS release in which
gnome-session-bin did not depend on dbus-x11, so it is plausible that
your system did not have dbus-x11 installed.  I have updated the
TurboVNC .deb manifest so that it now requires dbus-x11.


On 11/21/23 10:16 AM, DRC wrote:
> Please let me know if installing the dbus-x11 package fixed the issue.

Sorry for the delay!  Yes, I can confirm that installing dbus-x11 fixes the

issue!

Many Thanks for your help!

Felix