Firefox Accept-Language header does not follow preferences

[romain]

on a french firefox, possibly on all non english installs of firefox 43 on Ubuntu 15.10,
the Accept-Language header is set to en_US regardless of the language preferences.
It started with the upgrade to ff43, and the issue exists event when creating a new profile.

How to Reproduce :
Create a new profile on a firefox in french, go to any website, Accept-Language HTTP header does not contain "fr"
(I could reproduce the bug in a virtualized 15.10)

Workaround :
about:preferences#content > Languages: choose
Change order, click OK
Languages: choose (again) Change order back, click OK
Now the Accept-Language header is correctly set

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[janning (vygen-kicktipp)]

Same here, starts with version 43. The Accept Language header is set to "en-US,en;q=0.5"

[Cs-gon (cs-gon)]

This affect us too. Our accept languages are "de,en-US,en", as provided by the firefox-locale-de package. The accept language configuration shows up right in the configuration dialog in Firefox and in about:config (intl.accept_languages), but still Firefox only sends "en-US,en;q=0.5" in the HTTP header. This doesn't happen for all of our users though. But I have not been able to find out any differences between those installations/configurations yet.

It has something to do with the user profile, because when moving it away, and a new profile is generated the problem goes away, and when using the old profile again, the problem reappears. Though moving away/removing prefs.js does not make a difference.

In the past this problem often occurred the first time Firefox was started after an update. But now it seems to stick for some users, so even after restarting Firefox many times, the problem still persists.

This might not seem like a big issue, but it is for us. The problem is not only the language that is displayed, but also the other localization (dates, time of day, decimal point, etc.), when entering data into web GUIs, when printing, etc.. And this leads to all kinds of consecutive faults, when users don't realize this.

[Cs-gon (cs-gon)]

Some more info: Well I hope this is the same problem. We have the problem with newer Firefox versions right now (e.g. 45.0.1), we are using Ubuntu 14.04 though, but I guess the Firefox packages shouldn't differ much. The only difference I see is, that we don't have this problem with all our users, and a new profile seems to fix it, which is a bit different from the "how to reproduce" steps mentioned above.

[Hadrien (psydk)]

Confirmed on Ubuntu 16.04 (french) and Firefox 46.

This is really confusing to get served the english version of a web site instead of the french version. Sometimes there is no way or no obvious way to change the language on the website. Moreover, the website may offer a very different view assuming your are not french or located in France, giving you a wrong currency for example when you want to buy something.

I just lost one day on a website I wanted to subscribe to because the content did not make sense to me unless the correct Accept Language was set. I could subscribe without problems by using Chromium.

[Hadrien (psydk)]

I went to about:config. intl.accept_language is not overridden and is correctly set to: "fr, fr-fr, en-us, en"

If I override the option with the same string and a whitespace at the end, the Accept-Language HTTP field is correct.

If I reset the option back to "fr, fr-fr, en-us, en", the correct Accept-Language is still sent to the server. But if I restart Firefox the bug is back.

[Cyrille37 (cyrille37)]

Hi,
Exactly the same problem with FireFox 47.0 (Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0) on Ubuntu 14.04.4 LTS

with packages:
$ dpkg --get-selections |grep firefox
firefox install
firefox-locale-en install
firefox-locale-fr install

My pref is:
intl.accept_languages : fr, fr-fr, en-us, en

Http sent header:
Accept-Language : en-US,en;q=0.5

[Hadrien (psydk)]

upstream bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1005640

[Jarl (jarl-dk)]

This bug is confirmed on 17.04 with FF 53

[Paul White (paulw2u)]

Upstream report closed "RESOLVED FIXED" 2017-04-20
Target release Firefox 55
Marking as "Fix Released" to close