Firebug says “No Javascript on this page”, even though JavaScript does exist on the page

Question

Why does Firebug say there is No Javascript on this page when there are clearly loads of JavaScript on the page. I even reloaded the page several time to make s

Answer 1

I encountered No Javascript on this page after upgrading Firefox to ver 50.0, with Firebug ver 2.0.18. I tried refreshing Firefox, even completely uninstall Firefox and installed again. Nothing works for me.

A couple of hours later, I downgraded Firefox to 49.0.2, and voila, it works right away. I downloaded the old version here.