Why am I suddenly getting a “Blocked loading mixed active content” issue in Firefox?

Question

This morning, upon upgrading my Firefox browser to the latest version (from 22 to 23), some of the key aspects of my back office (website) stopped working.

Looking a

Answer 1

I found if you have issues with including or mixing your page with something like http://www.example.com, you can fix that by putting //www.example.com instead