VNC with XFCE freezes on Ubuntu 20.04

Question

Since 20.04 my headless xubuntu / xfce server freezes the vnc server after a short time, like after 5 minutes or so and certainly when not active. From the start of the vncserver the syslog shows

Oct 11 22:35:02 BS-Server2 systemd[1]: Started Run anacron jobs.
Oct 11 22:35:02 BS-Server2 anacron[93014]: Anacron 2.3 started on 2020-10-11
Oct 11 22:35:02 BS-Server2 anacron[93014]: Normal exit (0 jobs run)
Oct 11 22:35:02 BS-Server2 systemd[1]: anacron.service: Succeeded.
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] AppArmor D-Bus mediation is enabled
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.a11y.Bus' requested by ':1.0' (uid=1000 pid=93089 comm="xf
ce4-session " label="unconfined")
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.a11y.Bus'
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.xfce.Xfconf' requested by ':1.2' (uid=1000 pid=93089 comm=
"xfce4-session " label="unconfined")
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.xfce.Xfconf'
Oct 11 22:36:18 BS-Server2 org.a11y.Bus[93110]: dbus-daemon[93110]: Activating service name='org.a11y.atspi.Registry' requested by ':1.0' (uid=1000 pid=93089 comm=
"xfce4-session " label="unconfined")
Oct 11 22:36:18 BS-Server2 org.a11y.Bus[93110]: dbus-daemon[93110]: Successfully activated service 'org.a11y.atspi.Registry'
Oct 11 22:36:18 BS-Server2 org.a11y.Bus[93120]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.xfce.ScreenSaver' requested by ':1.2' (uid=1000 pid=93089
comm="xfce4-session " label="unconfined")
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.Daemon' requested by ':1.5' (uid=1000 pid=93124 co
mm="/usr/bin/xfce4-screensaver --no-daemon " label="unconfined")
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.Daemon'
Oct 11 22:36:18 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.xfce.ScreenSaver'
Oct 11 22:36:20 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.freedesktop.thumbnails.Thumbnailer1' requested by ':1.15'
(uid=1000 pid=93168 comm="xfdesktop --display :1.0 --sm-client-id 2f8228d1d-" label="unconfined")
Oct 11 22:36:20 BS-Server2 org.freedesktop.thumbnails.Thumbnailer1[93201]: error: XDG_RUNTIME_DIR not set in the environment.
Oct 11 22:36:20 BS-Server2 kernel: [115733.127180] xiccd[93203]: segfault at e4 ip 00005602078484f6 sp 00007ffdf326ff50 error 4 in xiccd[560207844000+5000]
Oct 11 22:36:20 BS-Server2 kernel: [115733.127196] Code: 00 eb 91 90 48 89 ef e8 e8 f8 ff ff eb c5 e8 01 cc ff ff 90 f3 0f 1e fa 55 53 48 89 fb 48 83 ec 08 e8 ce f
8 ff ff 48 8b 7b 08 <8b> 97 e4 00 00 00 85 d2 7e 34 31 ed 66 0f 1f 44 00 00 48 89 e8 ba
Oct 11 22:36:20 BS-Server2 kernel: [115733.257146] Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Oct 11 22:36:20 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.freedesktop.Notifications' requested by ':1.21' (uid=1000
pid=93208 comm="xfce4-power-manager " label="unconfined")
Oct 11 22:36:20 BS-Server2 kernel: [115733.304595] Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Oct 11 22:36:20 BS-Server2 kernel: [115733.317064] Lockdown: systemd-logind: hibernation is restricted; see man kernel_lockdown.7
Oct 11 22:36:20 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.freedesktop.Notifications'
Oct 11 22:36:20 BS-Server2 NetworkManager[812]: <info>  [1602448580.7144] agent-manager: agent[12c3d6c8e884b7fb,:1.130/org.freedesktop.nm-applet/1000]: agent regis
tered
Oct 11 22:36:21 BS-Server2 org.freedesktop.thumbnails.Thumbnailer1[93180]: Registered thumbnailer /usr/bin/gdk-pixbuf-thumbnailer -s %s %u %o
Oct 11 22:36:21 BS-Server2 org.freedesktop.thumbnails.Thumbnailer1[93180]: Registered thumbnailer atril-thumbnailer -s %s %u %o
Oct 11 22:36:21 BS-Server2 org.freedesktop.thumbnails.Thumbnailer1[93180]: Registered thumbnailer /usr/bin/gdk-pixbuf-thumbnailer -s %s %u %o
Oct 11 22:36:21 BS-Server2 org.freedesktop.thumbnails.Thumbnailer1[93180]: Registered thumbnailer gnome-thumbnail-font --size %s %u %o
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.UDisks2VolumeMonitor' requested by ':1.18' (uid=10
00 pid=93180 comm="/usr/lib/x86_64-linux-gnu/tumbler-1/tumblerd " label="unconfined")
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.UDisks2VolumeMonitor'
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.AfcVolumeMonitor' requested by ':1.18' (uid=1000 p
id=93180 comm="/usr/lib/x86_64-linux-gnu/tumbler-1/tumblerd " label="unconfined")
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.AfcVolumeMonitor'
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.GoaVolumeMonitor' requested by ':1.18' (uid=1000 p
id=93180 comm="/usr/lib/x86_64-linux-gnu/tumbler-1/tumblerd " label="unconfined")
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.GoaVolumeMonitor'
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.GPhoto2VolumeMonitor' requested by ':1.18' (uid=10
00 pid=93180 comm="/usr/lib/x86_64-linux-gnu/tumbler-1/tumblerd " label="unconfined")
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.GPhoto2VolumeMonitor'
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.MTPVolumeMonitor' requested by ':1.18' (uid=1000 p
id=93180 comm="/usr/lib/x86_64-linux-gnu/tumbler-1/tumblerd " label="unconfined")
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.MTPVolumeMonitor'
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.freedesktop.thumbnails.Thumbnailer1'
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Activating service name='org.gtk.vfs.Metadata' requested by ':1.15' (uid=1000 pid=93168
 comm="xfdesktop --display :1.0 --sm-client-id 2f8228d1d-" label="unconfined")
Oct 11 22:36:21 BS-Server2 dbus-daemon[93103]: [session uid=1000 pid=93101] Successfully activated service 'org.gtk.vfs.Metadata'
Oct 11 22:36:25 BS-Server2 kernel: [115738.266473] panel-6-systray[93172]: segfault at f8 ip 00007f5b3f656b66 sp 00007ffdcdb33948 error 4 in libgdk-3.so.0.2404.16[
7f5b3f633000+81000]
Oct 11 22:36:25 BS-Server2 kernel: [115738.266503] Code: 25 fe ff e9 57 fd ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 8b 87 f8 00 00 00 c3 0f 1f 40 0
0 f3 0f 1e fa 31 c0 <48> 39 bf f8 00 00 00 0f 94 c0 c3 66 66 2e 0f 1f 84 00 00 00 00 00
Oct 11 22:36:26 BS-Server2 kernel: [115738.861088] traps: nm-applet[93189] trap int3 ip:7f04ad3a20d5 sp:7ffc72c8b330 error:0 in libglib-2.0.so.0.6400.3[7f04ad36600
0+84000]
Oct 11 22:36:33 BS-Server2 org.xfce.ScreenSaver[93124]: Xlib:  extension "DPMS" missing on display ":1".
Oct 11 22:36:48 BS-Server2 org.xfce.ScreenSaver[93124]: Xlib:  extension "DPMS" missing on display ":1".
Oct 11 22:37:03 BS-Server2 org.xfce.ScreenSaver[93124]: Xlib:  extension "DPMS" missing on display ":1".

However when the server freezes, I do NOT get another error message, syslog only shows:

Oct 11 22:38:33 BS-Server2 org.xfce.ScreenSaver[93124]: message repeated 6 times: [ Xlib:  extension "DPMS" missing on display ":1".]
Oct 11 22:38:48 BS-Server2 org.xfce.ScreenSaver[93124]: Xlib:  extension "DPMS" missing on display ":1".

And it's stuck.

I am under the impression that the freezing happens when I am not working in the vnc window for a few minutes (like 5 minutes). Difficulty is there will be no error message.

Any ideas? The setup ran well for years up to Ubuntu 18. I specifically switched to xfce because of the fact that other vnc servers gave problems but now I'm stuck with no VNC - it's the cornerstone of my Ubuntu environment.

Solution

I uninstalled tightvncserver:

sudo aptitude remove tightvncserver

and installed tigervnc:

sudo aptitude install tigervnc

In my case I had to edit /etc/vnc.conf since the defaults didn't work for me, but YMMV.

After 10 minutes, no freezing, and the xfce4 windows are now drawn properly with their window borders and controls.

Comments

[Admin]

I'm experiencing the same problem -- vnc works, but freezes after a few minutes and needs to be killed and restarted. it's a pain because you lose your session. I'm on 20.04.2 LTS and have been experiencing this problem since I left 18.04 to 20.04.

[Frederik Boersma]

I do not have xrdp installed - I could install it but I am using VNC over SSH so I am not sure how xrdp would interact with that.

[Frederik Boersma]

Point is - VNC works but it sort of just dies after 5 minutes. Are those the same symptons / problems you have?

[Error404]

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

[Greenonline]

This is the same as your other answer: askubuntu.com/a/1372541/348964

[raspiduino]

That worked for me on Xubuntu 20.04. It seems that tightvnc is too old.