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: 
This is a winner for me:

```
/usr/bin/dbus-launch /usr/bin/gnome-terminal &

```

as learned [here](https://bbs.archlinux.org/viewtopic.php?pid=1828182#p1828182)
I had to combine answers from @TomH and @BarryPye. To get a gnome-terminal window:

```
LC_ALL=en_US.UTF-8 /usr/bin/dbus-launch gnome-terminal

```

In my case, the issue was occuring in a VNC session. I fixed it in my `~/.vnc/xstartup` by changing the window manager invocation to:

```
LC_ALL=en_US.UTF-8 /usr/bin/dbus-launch /bin/gnome-session

```

Then gnome-terminal starts directly from command or the gnome graphical launcher, without the need to extra dbus-launch commands.