I use i3 windows manager. Adding,
bindsym $mod+g exec /usr/bin/gnome-terminal -e "ranger" to the is config file to bind the $mod+g keys

When using the key combination $mod+g, a gnome-terminal starts but ranger crashes.

If I first open a gnome-terminal window and then execute ranger, the program starts and runs normally.

I am not sure if this helps.

ranger version: 1.6.1, executed with python 2.7.5
Locale: en_US.UTF-8
Current file: /home/jeff/anaconda3
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/ranger/core/main.py", line 133, in main
    fm.loop()
  File "/usr/lib/python2.7/site-packages/ranger/core/fm.py", line 310, in loop
    ui.redraw()
  File "/usr/lib/python2.7/site-packages/ranger/gui/ui.py", line 262, in redraw
    self.draw()
  File "/usr/lib/python2.7/site-packages/ranger/gui/ui.py", line 288, in draw
    DisplayableContainer.draw(self)
  File "/usr/lib/python2.7/site-packages/ranger/gui/displayable.py", line 246, in draw
    displayable.draw()
  File "/usr/lib/python2.7/site-packages/ranger/gui/widgets/titlebar.py", line 39, in draw
    self._print_result(self.result)
  File "/usr/lib/python2.7/site-packages/ranger/gui/widgets/titlebar.py", line 150, in _print_result
    self.color(*part.lst)
  File "/usr/lib/python2.7/site-packages/ranger/gui/curses_shortcuts.py", line 53, in color
    attr = self.settings.colorscheme.get_attr(*keys)
  File "/usr/lib/python2.7/site-packages/ranger/ext/cached_function.py", line 10, in inner_cached_function
    value = fnc(*args)
  File "/usr/lib/python2.7/site-packages/ranger/gui/colorscheme.py", line 67, in get_attr
    return attr | color_pair(get_color(fg, bg))
  File "/usr/lib/python2.7/site-packages/ranger/gui/color.py", line 26, in get_color
    curses.init_pair(size, fg, bg)
error: init_pair() returned ERR

ranger crashed.  Please report this traceback at:
http://savannah.nongnu.org/bugs/?group=ranger&func=additem