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 de

Answer 1

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.

Answer 2

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:

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.

Answer 4

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.

Answer 5

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..

Answer 6

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.