Firefox debugger breakpoint not working

Question

When I click on a line to set a break point, the break point line gets highlighted, then the break point highlight disappears.

Other than that, Firefox developer debug has been working fine.

Deicide

Is the breakpoint listed in the debugger in the right panel under "breakpoints"? – Leonteen

thanks MS, i had to COMPLETELY remove firefox and all mozilla folders and then reinstall. i could not just you add/remove programs, that dosnt remove enough to make for a total clean install. my breakpoints are working now. support.mozilla.org/en-US/kb/… – Deicide

Same problem for me. I did not find what causes this. I don't have such issue with the developer edition of Firefox. – Porphyria

I decided to try chrome for my mvc angular project. it works great, except, sometimes the debugger dosnt show all javascript files. HOWEVER, overall, using the chrome debugger is far more consistant than firefox. if you are using visual studio, you can run that debugger under on the chrome browser. it will display javascript and mvc controller breakpoints. You can use "start without debugging" in visual studio, and then evoke the chrome debugger itself. – Deicide

Answer 1

This might help people in the future without having to modify any js file:

Have you clicked the Deactivate breakpoints button? Pressing this will toggle breakpoints on/off.

If the icon is in blue, it means the breakpoints will be de-activated.

Note: I have noticed that in some sessions the toggle is activated although not blue, a refresh of the page solved this.

Lukin

@ChristopheRoussy I found this madness, too. Not to mention that sometimes it's active but doesn't show as active :facepalm: – Lukin

Answer 2

This just happened to me in Firefox 60.3.0. The tip about removing the Mozilla folder led me to a better solution, which is to edit the prefs.js file in the Mozilla profile folder. (In my system this was in C:\Users\xxx\AppData\Roaming\Mozilla\Firefox\Profiles\xxx.default)

I deleted all of the lines in prefs.js that began with

user_pref("devtools.

e.g.

user_pref("devtools.toolsidebar-height.inspector", 350);

user_pref("devtools.toolsidebar-width.inspector", 350);

This fixed the problem while preserving all my bookmarks, saved passwords, etc. The lines in prefs.js were recreated when I next ran the debugger.

Incline

This solved the issue for me. Make sure you close Firefox completely before even opening the prefs.js file for editing, then save and close the changed file before opening Firefox again. – Senna

Unfortunately, this didn't work for me — FF 64.0. )= – Irmine

Worked for me, FF70.0.1, but I think I found the culprit in the process. It would appear the skip pausing button mentioned above doesn't always show the right state. I had it on and then refreshed the page, it was showing as off (also the breakpoints where showing as regular blue instead of pale) but it was actually on in prefs: user_pref("devtools.debugger.skip-pausing", true); Simply turning it on and off seems to fix the problem as well. – Ume

Answer 3

I my case I have mistakenly enabled 'Blackbox source' on a file (in right click menu). When I disabled it then the breakponts works again.

Rimskykorsakov

I had a file not in the blackbox, but after I put it in the blackbox and then removed, the problem was solved. – Spread

Answer 4

In my case it was 2 check-boxes to check:

Maclay

Answer 5

I ran into this problem, or a variant of it as well. For me, it was because webpack was defaulting to setting devtool to "eval". This broke stopping at breakpoints in Firefox for me. Changing that setting to "source-map" resolved the issue, though I suspect most other non-eval options would work fine as well.

I noticed this because I looked in the generated JS file and noticed everything was put into eval() calls.

Masoretic

This should be the accepted answer – Sahaptin

Answer 6

I just encountered the same problem - Firefox Quantum 60 on Ubuntu.

Solution for me was to delete the ~/.mozilla folder for my account. Lost all my bookmarks, history, settings, etc., but can now set breakpoints again.

Gamez

This was my situation exactly (well FFQ 62.0, but still). So far, deleting ~/.mozilla seems to have done the trick for me. – Billet

This is like blowing up your house to shoo out a stray cat. – Senna

Thanks for the feedback Walf. If you have a more elegant solution feel free to include the details below. – Gamez

Works also for me – Corley

Answer 7

Also, check the console for errors. I've experienced this issue (can't set a breakpoint) when there is an error elsewhere in the page..

Mohenjodaro

Answer 8

I just stumbled across a similar problem. In my case, it was the eye on the lower left of the debugger window.

The breakpoint vanishes after clicking the eye:

Update:
And another way to blackbox a source:

Putupon

I just noticed that's @madox2's answer, but I activated the "Blackbox source" function in a different way. I'll add the second way to my answer. – Putupon