Question: I have Ubuntu-Gnome 14.04 (Gnome 3.12.2).

When I try to run `gnome-terminal` by following command :

```
$ gnome-terminal
Error constructing proxy for org.gnome.Terminal: /org/gnome/Terminal/Factory0: 
Error calling StartServiceByName for org.gnome.Terminal:
GDBus.Error:org.freedesktop.DBus.Error.Spawn.ChildExited: 
Process /usr/lib/gnome-terminal/gnome-terminal-server exited with status 8

```

Answer: 
I had this problem when I created a new Ubuntu 16.04.3 LTS Desktop. The fix was to edit the `/etc/default/locale` file by adding the following line to the end of the file:

```
LC_ALL="en_US.UTF-8"

```

Then reboot and the problem was gone.
Another cause of the problem is that new preferences have been activated at the start of the session, check "Applications at startup" Preferences