Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita", error on executing the the python script with pygtk module

I recently added the the Macbuntu theme in my Ubuntu 16.04 from the site [Noobslab][1], In am learning GTK+ for Python too (PyGTK), earlier when I ran the test programs I made run quietly without showing any error in stderr stream but after I installed the theme, I am getting a warning

(radio_button.py:6696): Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita",
(radio_button.py:6696): Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita",

For example when I ran the script of radio_button.py.

I want to fix this error, without uninstalling the theme.

Solution 1:

I had the same issue

sudo apt install gnome-themes-standard

Fixed the issue.

Solution 2:

In order to remove this warning (you can live with it, it is not causing any problem) the solution above did not worked for me. I had to, on top of installing gnome-themes-standard, do the following: $ sudo apt-get install gnome-themes-extra gnome-themes-extra:i386

In my case was the 32 bit architecture version that did the trick.