vnc session crashes after some time

Sys-Info:
lsb_release -rd
Description: Ubuntu 17.10
Release: 17.10

Packages:
apt-cache policy tightvncserver
tightvncserver:
  Installiert: (keine)
  Installationskandidat: 1.3.10-0ubuntu3
  Versionstabelle:
     1.3.10-0ubuntu3 500
        500 http://ch.archive.ubuntu.com/ubuntu artful/universe amd64 Packages

apt-cache policy xfce4-session
xfce4-session:
  Installiert: 4.12.1-3ubuntu3
  Installationskandidat: 4.12.1-3ubuntu3
  Versionstabelle:
 *** 4.12.1-3ubuntu3 500
        500 http://ch.archive.ubuntu.com/ubuntu artful/universe amd64 Packages
        100 /var/lib/dpkg/status

Hello after updating to Ubuntu 17.10 / Artful my vnc session / xfce sessions keeps on crashing after some time ... some time can be between 5 mins or 24 hours.

It doesn't matter if it is a vm or a physical machine.

It always starts with the following messages ( it is taken from vnc log )

xfce4-session-Message: Got disconnected from D-Bus. Unless this happened during session shutdown, this is probably a bad thing.

** (zeitgeist-datahub:6142): WARNING **: zeitgeist-datahub.vala:227: Unable to get name "org.gnome.zeitgeist.datahub" on the bus!

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

(xfsettingsd:6129): xfconf-CRITICAL **: IA__xfconf_channel_set_bool: assertion 'XFCONF_IS_CHANNEL(channel) && property' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed

** (xfsettingsd:6129): CRITICAL **: dbus_g_proxy_disconnect_signal: assertion '!DBUS_G_PROXY_DESTROYED (proxy)' failed
The program 'wrapper-1.0' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadWindow (invalid Window parameter)'.
  (Details: serial 1011 error_code 3 request_code 4 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

(xfce4-panel:5596): xfce4-panel-WARNING **: Failed to connect to the D-BUS session bus: Failed to connect to socket /run/user/1000/bus: Datei oder Verzeichnis nicht gefunden
xfce4-panel: Es ist bereits eine laufende Instanz vorhanden

After that when I connect to the vnc session i just see the grey x-server background.