Certain applications won't start with Xpra v5.0

[KondorIstvan]

Describe the bug
Gnome-terminal and gnome-characters fail to open in seamless mode.

To Reproduce
Steps to reproduce the behavior:

1. xpra start :12 (on RHEL 8.7)
2. attach client using gui (on Windows 10)
3. Click the tray icon, navigate to start "Terminal" or "Characters". They should pop up on the Windows machine, but nothing happens.

System Information (please complete the following information):

• Server OS: [RHEL 8.7]
• Client OS: [Windows 10]
• Xpra Server Version [5.0]
• Xpra Client Version [5.0]

Additional context
When starting gnome-terminal I get the following text in journalctl:

> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local xpra[10221]: 2023-09-01 13:03:00,233 started command `/usr/bin/vglrun gnome-terminal` with pid 11238
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local dbus-daemon[5452]: [session uid=1002 pid=5452] Activating via systemd: service name='org.gnome.Terminal' unit='gnome-terminal-server.service' requested by ':1.101' (uid=1002 pid=11238 comm="gnome-terminal ")
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local systemd[5323]: Starting GNOME Terminal Server...
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local gnome-terminal-server[11254]: Unable to init server: Could not connect: Connection refused
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local gnome-terminal-server[11254]: Failed to parse arguments: Cannot open display:
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local systemd[5323]: gnome-terminal-server.service: Main process exited, code=exited, status=10/n/a
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local systemd[5323]: gnome-terminal-server.service: Failed with result 'exit-code'.
> Sep 01 13:03:00 ZETLNXCFD01.sdibs.local systemd[5323]: Failed to start GNOME Terminal Server.

For gnome-characters I see:

> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local xpra[10221]: 2023-09-01 13:15:47,540 started command `/usr/bin/vglrun gapplication launch org.gnome.Characters` with pid 12664
> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local dbus-daemon[5452]: [session uid=1002 pid=5452] Activating service name='org.gnome.Characters' requested by ':1.188' (uid=1002 pid=12664 comm="gapplication launch org.gnome.Characters ")
> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local dbus-daemon[5452]: [session uid=1002 pid=5452] Successfully activated service 'org.gnome.Characters'
> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local org.gnome.Characters[12681]: Unable to init server: Could not connect: Connection refused
> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local org.gnome.Chara[12681]: **cannot open display: :2**
> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local xpra[12664]: error sending Activate message to application: GDBus.Error:org.freedesktop.DBus.Error.NoReply: Message recipient disconnected from message bus without replying
> Sep 01 13:15:47 ZETLNXCFD01.sdibs.local xpra[10221]: 2023-09-01 13:15:47,626 child 'Characters' with pid 12664 has terminated

So it even explicitly wants to start on :2 but xpra is correctly working

> $ xpra list
> Found the following xpra sessions:
> /run/user/1002/xpra/12:
>         LIVE session at :12
> /run/user/1002/xpra:
>         LIVE session at :12
> /home/i.kondor/.xpra:
>         LIVE session at :12

Very interestingly if I have a running VNC session with the same user but on a different display (:2), a terminal window opens there and remains functional even after the log says (see below) that it terminated. Characters does the same.

> Sep 01 12:53:13 ZETLNXCFD01.sdibs.local xpra[10221]: 2023-09-01 12:53:13,821 started command `/usr/bin/vglrun gnome-terminal` with pid 10874
> Sep 01 12:53:13 ZETLNXCFD01.sdibs.local xpra[10874]: # watch_fast: "/org/gnome/terminal/legacy/" (establishing: 0, active: 0)
> Sep 01 12:53:13 ZETLNXCFD01.sdibs.local xpra[10874]: # unwatch_fast: "/org/gnome/terminal/legacy/" (active: 0, establishing: 1)
> Sep 01 12:53:13 ZETLNXCFD01.sdibs.local xpra[10874]: # watch_established: "/org/gnome/terminal/legacy/" (establishing: 0)
> Sep 01 12:53:13 ZETLNXCFD01.sdibs.local xpra[10221]: 2023-09-01 12:53:13,880 child 'Terminal' with pid 10874 has terminated

All other, including 3D, applications work. Virtualgl also works fine, cuda is detected and glxinfo prints everything correctly when started in xterm.

[totaam]

Very likely to be a duplicate of #3976

[KondorIstvan]

Sounds good, thank you! I'll report back after the release of v5.0.1.

[KondorIstvan]

Maybe #3109 was also caused by #3976?
If yes, the comment about gnome-terminal under 'Problems' section in the FAQ should also become obsolete, I reckon.

v5.0.1 once again has not yet been built for RHEL distros... Is there a bug or do you have to manually start them?

[totaam]

Maybe #3109 was also caused by #3976?

Very unlikely - AFAIK, this regression was the first time that dbus failed to start.

Is there a bug or do you have to manually start them?

Xpra-org/repo-build-scripts#11

[KondorIstvan]

I can confirm that v5.0.1 fixed the issue.

Thank you so much for your hard work!