How to fix error Xlib.error.DisplayConnectionError: Can't connect to display ":0": b'No protocol specified\n'

Question

I'm making some program with python3 and XLib.

On my PC with Ubuntu 14.04 everything works fine but when I try to run my app in my notebook with manualy installed Xorg I get exception:

Xlib.error.DisplayConnectionError: Can't connect to display ":0": b'No protocol specified\n'

on line:

self.__display = Xlib.display.Display()

What's going on here? How to fix this that it could work on every Linux?

Edit:

This does not look like duplicate of X11: run a gnome app as another user. On my both computers I have same users and groups, so this problem is probably not connected with lack of permissions to run my program.

It must be something else something with bad configuration of X.

Answer 1

Temporary workaround is

$ xhost +

http://ubuntuforums.org/showthread.php?t=2290602