My version of Firefox Quantum is 63.0.3 (64-bit) on Windows 10. When I open debugger, I can't see any source files. I can confirm that JS is enabled and there are JS files on the site/page.

Perhaps, there's some setting that I need to correct.

My version of Firefox Quantum is 63.0.3 (64-bit) on Windows 10. When I open debugger, I can't see any source files. I can confirm that JS is enabled and there are JS files on the site/page.

Perhaps, there's some setting that I need to correct.

• javascript
• debugging
• firefox

• Reload the page with the debugger open? – Bergi Commented Nov 25, 2018 at 17:27
• No. Reload doesn't help. I'm thinking only reinstallation of Firefox will work. – Arvind Padmanabhan Commented Nov 26, 2018 at 3:51
• 1 I am currently facing the same problem in Quantum v64. Did you find a solution to your problem? – SaschaM78 Commented Apr 12, 2019 at 12:46
• I uninstalled Firefox completely. Reinstalled it. During reinstall, took the option of factory defaults without importing any customization from old install. Works. Back to normal. – Arvind Padmanabhan Commented May 9, 2019 at 13:11

3 Answers 3

The bug with blank of file source tree in the debugger is still actual in Firefox Developer Edition 83.0b10 (64-bit), I've seen it several times in last days. Disable cache, reload page and restart Firefox do not help, but I found worked solution - just copy the URL and run it in a new tab.

In the posted image the whole debugger tab is empty, instead of just missing a particular source file. This is caused by corruption of either/both devtools.debugger.tabs or devtools.debugger.pending-selected-location containing things that messes up the tabs preference. Using the reset option for those preferences should revert those back to either an empty JSON array or empty object. Closing and opening toolbox or restarting Firefox after resetting these preferences should restore the debugger.

Note that if the whole inspector stays blank (so no Debugger tab, no Inspector tab, not even a close button) it could be caused by devtools.telemetry.tools.opened.version no longer making sense.

Creating a new profile (or reinstalling Firefox without importing an existing profile of course takes care of all these preferences and avoids having to edit any preferences by hand.

Once I faced the same problem. But it was more 'magical'

I got my file (example.js) in FF Debugger, but breakpoints where not working. I saw the requests send by this js code, but couldn't debug it

The reason was: in project the file example.js was loaded on page, and after that example.js was loaded the second time by GET request to server

So, it was 'overriden', and I could see example.js in debugger, but it wasn't working, because example.js loaded by GET request was working (and you can't debug it, really)

So - maby your file is just loaded by GET request? You will not see it in debugger...