How can I activate the Firefox debugger?

Question

While debugging a JavaScript program I was writing with Firebug, the Script panel stopped working and I got the following message:

I went through all menus and sub-menus I could find but didn't see a option to re-enable this feature. The console.log() command doesn't work in Firebug as well (while it does work in the built-in devtools' console).

How can I re-activate the Firebug Script panel? What may have caused this?

Answer 1

This may have different causes. One of them is described in issue 5646, which is related to going back and forward in the browser history.

In such cases it normally requires a browser restart to work again.

Note that Firebug up to version 1.12 is based on an old debugger API exposed by Firefox called JSD, which is unmaintained and buggy. Since version 2.0 Firebug uses a new debugger API, which fixes this problem.

Answer 2

Coincidentally, I just "fixed" the same problem with my Firebug. I went through re-installs, options resets and such and nothing helped.

After some investigation it boiled down to the content of the page I was debugging. I have a function called by jQuery when page load is finished:

<script>
$(onPageLoad);
</script>

Now, this function asks user to enter his name using prompt() function. It appeared that Firebug wouldn't activate script panel until prompt() is closed. That is not a problem when you have just one page opened since you just close the dialog and everything works. However, it is a problem when you have two same pages opened. Script panel is non-operational until you close both prompts.

Answer 3

I was facing this problem recently. I found that my Firebug was not getting updated because my Firefox was stuck on 29.x. Once I updated my Firefox the new Firebug got installed. It supports only Firefox 30+.

Note: I was using OSX v1.9.3.

Answer 4

I was having same problem, and, thanks to Roman Guralink, I figured out that the the dialogue Firefox prompts you to insert the master password was the cause. When you set a master password for all password stored, FFox usually opens a dialogue to ask it just after program started. BUT, sometimes this dialogu goes behind the main window, and you don't notice it is there.