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

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

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 sure but it still show the same message.
It never used to do that before, but all of a sudden it misbehaves.
Is it because of some configuration issues or because of something else?

Solutions/Answers:

Solution 1:

As of Firefox version 50, it seems that Firebug will no longer work as Mozilla are migrating to Firefox Devtools. The tab Tools/Web Developer has a ‘debugger’ option. See this page for a discussion on the migration. Read all the posts dated 19 November for further information.

It seems to me that the option gives less functionality but Firebug per se is never going to be fixed for Firefox 50 and beyond

Solution 2:

EDIT 2017 April

This answer is now outdated and I’m not even testing it anymore because I’m no longer using Firebug (a shame, I loved it years ago in a time it was The tool of trade for web developing).

EDIT 2014 November

The original answer is now more than a year outdated due to firebug evolution.
Thanks to @AmadeusDrZaius to keep it on tracks

Answer for outdated firebug versions
For anyone still with this problem after updating Firebug.
Just click Clear Activation List option inside the Firebug menu.

For those who can’t find it, note that “Clear Activation List” shows up in the dropdown from the Firebug icon in the toolbar, but not the Tools > Web Developer > Firebug menu.

Firebug dropdown: Clear Activation List

I guess due to the bug previous hitting your working page it stays listed as “no activate FB for this site please”.

Solution 3:

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.

Solution 4:

I tried everything on this list and nothing worked for me except resetting Firefox like so:

https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-problems

Solution 5:

I realize there are already 10 answers to this question, but in my case none of them helped. I’m running Firefox version 39.0 and Firebug version 2.0.11. The only fix is to completely restart Firefox (i.e. not just the tab or instance with the problem).

Perhaps it’s due to Firefox’s over-usage of memory, or maybe there’s a bug in Firebug. I can’t speak to that, but what I do know is it didn’t work. I killed Firefox, opened the exact same page again with no changes made and now it works. This has happened to me numerous times and a complete restart always fixes it, but that’s the only thing that does.

Solution 6:

Since Firefox 49.0 and Firebug 2.0.18 the Script panel is broken. This is due to some internal Firefox API changes. And because Firebug is officially discontinued, this unfortunately won’t get fixed anymore.

There was also a bug in Firebug 2.0.11 (and below) in combination with Firefox 39.0 causing this problem. This bug is filed as issue 7918.
It happens when the Script panel is enabled and you close Firebug and reopen it.

You can see two related error messages logged to the Browser Console (can be opened via Ctrl+Shift+J or Firebug menu > Developer > Browser Console):

error occurred while processing ‘attach: TypeError: docShell is null
Stack: getChildDocShells@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/server/actors/webbrowser.js:53:7

and

onPacket threw an exception: Error: Server did not specify an actor, dropping packet: {“error”:”unknownError”,”message”:”error occurred while processing ‘attach: TypeError: docShell is null\nStack: getChildDocShells@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/server/actors/webbrowser.js:53:7

Solution:

The only solution until this bug is fixed is to restart Firefox completely.