I have just upgraded from Ubuntu 12.04 LTS to Ubuntu 14.04 LTS running GNOME. The upgrade went smoothly.
My problem is that I cannot tweak the themes with gnome-tweak-tool. When I load gnome-tweak-tool I get the following error messages:
WARNING : Shell not installed or running INFO : GSettings missing key org.gnome.nautilus.desktop (key computer-icon-visible) WARNING : Error detecting shell Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_group_shell_extensions.py", line 284, in __init__ raise Exception("Shell not running or DBus service not available") Exception: Shell not running or DBus service not available WARNING : Shell not running
The gnome-tweak-tool windows are available but theme parameter changes in the Appearance tab do not work (you can write them in, but no effect and the default is restored upon exit).
The same problem occurs whether logged in with Metacity, Compiz, Ubuntu or GNOME.
When I run:
if pgrep gnome-shell; then echo GNOME shell is running; else echo Nope not running;fi it answers
Nope not running
When I log in as another user with root privileges, the same error and gnome-tweak-tool dysfunction occur.
I have now solved this problem. I can launch a functional Gnome Tweak Tool under Ubuntu 14.04 (or on another computer running 16.04 which presented the same problem) by entering "gnome-tweak-tool" in the Alt + F2 command line from any of the desktop flavours (GNOME, Ubuntu, Compiz, Metacity), but NOT from either a normal or a root terminal (which is widely implied on the web to be a valid method)!