Reference for this, please? Because I see no bugs filed on FF regarding brotli apart from https://bugzilla.mozilla.org/show_bug.cgi?id=1222541 and https://bugzilla.mozilla.org/show_bug.cgi?id=1207234 neither of which seems to match your problem description. I'm happy to get a bug filed for you so whatever problem this is can be fixed, but I need a bit more to go on here...

I did look around for known brotli+Firefox+nginx issues, but the only one that comes up is https://bugzilla.mozilla.org/show_bug.cgi?id=1215724 which was fixed in shipping Firefox months ago, so I'm assuming that's not the one you're talking about.

Sure, there is no official bug for this. The only way to see it is to check the dates when the new API was applied - its far too late after releasing versions already supporting brotli, but this commit was not backported anywhere so in a real life, its broken in FF. Just get an nginx, nginx brotli module from google and use FF 45. Good luck :)

https://hg.mozilla.org/releases/mozilla-aurora/log/10e1774de...

> but this commit was not backported anywhere

Which commit are you talking about, exactly? Bug 1242904 was backported to Firefox 45, and everything else I see at http://hg.mozilla.org/mozilla-central/filelog/tip/modules/br... as of today (which is the same as <http://hg.mozilla.org/mozilla-central/filelog/ea6298e1b4f7/m...) was checked in way before 45....

Ah, looks like the part of bug 1242904 that was backported is just the security fix, not the entire library version update and the version update is in 46. So what you could be seeing is something like https://bugzilla.mozilla.org/show_bug.cgi?id=1254411

Of course the version update wasn't supposed to change the on-the-wire behavior... or so the library authors claimed. :(