Underpass said

The problem has happened the first time upon upgrading from 53b10 to 53RC1 and has not been solved ever since.

Those are beta versions. Are you still having problems with normal Firefox? Download Firefox For All languages And Systems {web link}

Thanks. Obviously, I've also tried with the stable version (when I said "ever since" I meant "with every subsequent version") and the problem still happens.

I have to repeat: please, I need higher level support since the basic troubleshooting steps have already been performed. Thanks.

It may be something about the current version is causing the problem.

Install Older Version Of Firefox {web link} Be sure to read everything here.

If you still want to downgrade, look under; I still want to downgrade. Click the Directory of other versions and languages link. Look for the directory of the version that you want. But, remember that old versions may have security issues.

You should also check out Firefox; Extended Support Release {web link} ESR Notes System Requirements

Excuse me, I've been using Firefox since 2003 and contributing to SUMO since 2008, translating some 300 articles or so.

Can you please stop treating me like a newcomer? I need a higher level support.

Thanks.

I called for more help.

are you sure about the regression range? because between beta 10 and rc1 there was only a single change: security.tls.version.max was set from 4 back to 3 (and therefore to the state it was on for a while now already). https://hg.mozilla.org/releases/mozilla-release/pushloghtml?fromchange=FIREFOX_53_0b10_BUILD1&tochange=213b1f8f2409

Thanks for the answer: I am really sure about the regression range since I stepped back for a while to 53b10 and had no issue.

I will try tomorrow morning and let you know.

I've just tried this morning to set the preference security.tls.version.max from 4 to 3: the problem still occurs.

If you wish, I can install again version 53b10 to confirm the behaviour.

ok, maybe my query was wrong, as manually looking at the changes around the time at https://hg.mozilla.org/releases/mozilla-release/shortlog brings up much more. one obvious proxy related patch would be https://bugzilla.mozilla.org/show_bug.cgi?id=1348841 but to be honest i would just file a bug and tag it with the keyword "regression" to get some traction on it and then engineers more knowledgeable than us will look into the matter.

This is the bug I've opened

https://bugzilla.mozilla.org/show_bug.cgi?id=1363030

Do you have manual, system or automatic proxy configuration in the Preferences?

TyDraniu ha detto

Do you have manual, system or automatic proxy configuration in the Preferences?

Yes, I use a .PAC file. But the same happens even if I use the host:port configuration.

@philipp: the problem is also verified on Firefox 54

I use to have similar problem in Nightly 2017-04-13. Turning to autodetect proxy did help.

@Underpass :
Almost afraid to ask, but have you gone over this McAfee article :
How to use PAC files with Web Gateway

Happy112 ha detto

@Underpass :
Almost afraid to ask, but have you gone over this McAfee article :
How to use PAC files with Web Gateway

No worries... This is a document aimed to the people who manages the proxy, in which is explained how to implement this solution. In my case, the PAC file has already been created, and is working for all the browsers. ;)

TyDraniu ha detto

I use to have similar problem in Nightly 2017-04-13. Turning to autodetect proxy did help.

Thanks but we do not have this feature enabled on our network.

Hello, could this bug be related to mine?

https://bugzilla.mozilla.org/show_bug.cgi?id=1360574

The bug has been fixed in Nightly and Beta and soon will be solved in release and ESR.

Thanks for the attention