Problems with icons, themes, nautilus on VNCServer after upgrade from Ubuntu 16.04 to 18.04

Problem:

After upgrading one of my VMs from Ubuntu 16.04 to Ubuntu 18.04, I’m having various GUI problems on VNC server.

Note: I was able to upgrade another VM, which is a 1 year old clone of this very same machine, without any issues.

1. ubuntu-mono-dark icons don’t work. Pixbuff loaders cache fails with the error:

g_module_open() failed for
/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders/libpixbufloader-svg.so:
/usr/lib/x86_64-linux-gnu/libxcb-shm.so.0: undefined symbol:
xcb_send_request_with_fds

Update: After a few days on this, I was finally able to fix this problem by running the following commands before upgrading:

apt --reinstall install libxcb1 
apt --reinstall install libxcb-shm0 
apt --reinstall install libgdk-pixbuf2.0-0 
apt -y install libgdk-pixbuf2.0-dev 
gdk-pixbuf-query-loaders --update-cache 
apt -y purge g++-5 
dconf reset -f /org/gnome/
apt autoremove

2. Nautilus takes forever to load and eventually timeouts with the error:

gnome-session[11721]: gnome-session-binary[11721]: WARNING: Application ‘nautilus-classic.desktop’ failed to register before timeout

gnome-session-binary[11721]: Unrecoverable failure in required component nautilus-classic.desktop

gnome-session[11721]: gnome-session-binary[11721]: CRITICAL: We failed, but the fail whale is dead. Sorry….

metacity[11983]: CurrentTime used to choose focus window; focus window may not be correct.

kernel: [236.762533] rfkill: input handler enabled

When it does, some programs like terminal and MySQL Workbench mysteriously lose their title bar and their minimize, maximize and close buttons. These programs also start opening on the top left corner of the screen. It also becomes impossible to move the windows of some of these affected programs like MySQL Workbench.

Before Nautilus Timeout

After Nautilus Timeout

What I Tried:

Full reinstall of gnome, metacity, nautilus and vncserver with:

apt -y purge ubuntu-desktop ubuntu-gnome-desktop gnome-core gnome-panel gnome-terminal gnome-settings-daemon metacity nautilus autocutsel vnc4server
apt autoremove
apt -y purge *desktop* *gnome* *metacity* *nautilus* 
apt autoremove
rm -vr .cache/tracker .config/nautilus .config/gnome-session .config/gtk* .gconf .gvfs .vnc .Xauthority
reboot
apt -y install ubuntu-desktop ubuntu-gnome-desktop gnome-core gnome-panel gnome-terminal gnome-settings-daemon metacity nautilus autocutsel vnc4server

I did a lot of other small things, including reinstall the snap packages and changing the VNC Server configuration, but none of them had any effect.

VNC Server Configuration:

#!/bin/bash

unset DBUS_SESSION_BUS_ADDRESS

xsetroot -solid grey
vncconfig -nowin &
autocutsel -fork

export XKL_XMODMAP_DISABLE=1
export XDG_CURRENT_DESKTOP="GNOME-Flashback:GNOME"
export XDG_MENU_PREFIX="gnome-flashback-"

gnome-session --session=gnome-flashback-metacity --disable-acceleration-check &

Suggestions?

Answer

Attribution
Source : Link , Question Author : js1018 , Answer Author : js1018