Last I reported, the future of Firefox’s Windows XP support was uncertain, even given long-standing plans for its removal.

With the filing of bug 1305453 and the commensurate discussion on firefox-dev, things are now much more certain. Firefox will (pending approval) be ending support for Windows XP and Windows Vista in Firefox 53 (scheduled release date: April 18, 2017).

Well, thanks for tuning in. I guess I can wrap up these posts and…

Okay, yes, you’re right. It isn’t that simple.

First, the actual day that Windows XP and Windows Vista users will cease getting Firefox updates is actually much later than April of 2017. Instead, those users will continue to receive security updates until April of 2018 because the version of Firefox 52 they’ll be getting is an Extended Support Release.

What is Firefox Extended Support Release (ESR)? It’s a version of Firefox for enterprises and other risk-averse users that receives security (and only security) updates for one year after initial release. This allows these change-weary users to still chose Firefox without having to consider how to support a major version release every six-to-eight weeks.

Windows XP and Vista users will be shunted from the normal roughly-six-weeks-per-version “Release” channel to the “ESR” channel for 52. New installs on Windows XP and Vista at that time will also be for ESR 52. This should ensure that our decreasing Windows XP+Vista userbase will be supported until they’ve finished diminishing into…

…well, okay that’s not simple either. In absolute terms, our Windows XP userbase has actually increased over the past six months or so. Some if not all of this is the end of the well-documented slump we see in user population over the Northern-hemisphere Summer (we’re now coming back up to Fall-Winter-Spring numbers). It is also possible that we’ve seen some ex-Chrome users fleeing Google’s drop of support from earlier this year.

Deseasonalized numbers for just WinXP users are hard to come by, so this is fairly speculative. One thing that’s for certain is that the diminishing Windows XP userbase trend I had previously observed (and was counting on seeing continue) is no longer in evidence.

So what happens if we reach April of 2018 and we still have millions and millions of Windows XP users still relying on Firefox to provide them with a safe way to navigate the increasingly-hostile environment of the Web?

No idea. I guess this means I’ll be continuing to blog about WinXP for a couple years yet.

:chutten