After updating Kali, the "manual proxy configuration" of firefox does not work anymor

[centaur]

After updating Kali, the "manual proxy configuration" of firefox does not work anymore.
Before of the update there was Iceweasel and it worked correctly with the following settings.
After update, I found Firefox ESR (not working with the followings ettings).

I did not find any solution in Kali Documentation page (or I did not see it), neither in Internet (where I only
found to flag "No proxy"). With "no proxy" i do not have any error and I can connect, but I need to use "manual proxy congifuration".

I tried to do some search in the Kalì forum (several (sub)combinations of the string
"The proxy server is refusing connections") without success.
(Though this error do not raise when using "system proxy settings" in firefox).

Settings used for "manual proxy configuration" of firefox : 127.0.0.1:8080 for all protocols.

I suspect with update some Kalì setting was changed (or firefox one?), but i do not how to look for them.

Kali version: 4.6.0-kali1-amd64
Kali installation: HDD
Basic output of commands:
1) let me know if you need some particular command, since with "no proxy" all works fine.
2) iptables -S = -P INPUT ACCEPT -P FORWARD ACCEPT -P OUTPUT ACCEPT
Error message: The proxy server is refusing connections
Links to the same problem (if any): I did not find.
Solutions tried and their results:
1) tried Firefox resfresh, no results (nothing changed)
2) in the "manual proxy configuration" of firefox "No proxy for:" left blank, no results (nothing changed)
3) in Kalì in "All settings -> network -> network proxy" tried several settings, still no results
4) tried to use socks v4 and v5 and different ports in the "manual proxy configuration" of firefox, no results

Sorry for my naive question.
Thank you for any help.

[grid]

I'm not using any iptables rules, but haven't seen this problem myself. I'm able to proxy BurpSuite through Firefox without any problems.

The only proxy settings I'm using are in Firefox, same as yours.

[centaur]

Hi grid, thank you for your answer. I am not using iptables neither (I only reported the output to show that the firewall is set to ACCEPT and that it is not its fault to block firerox; I also flushed iptables, just to try, also if I already knew that nothing would be changed). During the update something changed (such as SELinux or something like that and this prevent me to use localhost:8080 or 127.0.0.1:8080). Continuing my search to understand the problem. Thank you again.

[iojymbo]

Do you have a process listening on 127.0.0.1:8080 ?

[grid]

No problem, centaur iojymbo has a good suggestion, maybe there's something on port 8080 that's interfering.

[centaur]

Hi, thanks for your answers. Good hint, but, No, netstat doesn't indicate something running on port 8080.
With different settings I discovered how to make things work (on firefox i set "use system proxy" and in onother application i set the similar field accordingly), BUT i am not satisfied because I did not understand what happened that changed the things.

[centaur]

Never mind! It was not at all update problem, it was me!
I attempted distractly to set the browser (and try it) BEFORE of the proxy listener.
Sorry (I should be whipped for this)
Thank you again

[iojymbo]

No problem mate, we learn everyday too !