Windows XP and Vista Long Term Support Plan

Peter Dolanjski pdolanjski at
Wed Oct 12 19:16:08 UTC 2016

Hello All,

*tl;dr: Tentative plan is to move Windows XP/Vista users to ESR 52.  Feel
free to comment/discuss.*

In this email, I will lay out a tentative long term plan for supporting
Windows XP and Vista users.  The point of this email is to solicit feedback
about the plan from a broader audience.  I am purposefully keeping the
email somewhat high level, but if you have specific questions about the
details, I'm sure various folks on the engineering/release engineering
teams can help answer them.

If you have relevant information to include in the bug you can find it
here: *Move Windows XP and Vista to Firefox ESR 52*
I realize the discussion on this topic could get lively (which is
completely understandable) - I just ask that you keep in mind good intent.
We hope to finalize plans over the next few weeks.

Continue to provide an excellent browsing experience and ongoing security
updates to Windows XP and Vista users (inclusive of current Firefox users
and users on browsers which are no longer supported who want to switch).
At the same time, reduce the opportunity cost of supporting XP and Vista
(15 and 9 years since release, respectively).

*Tentative Plan*

   - Move Windows XP and Vista users to an Extended Support Release
   <> when v52 branches
   - Continue to provide security updates for the life of ESR 52 (well into
   - Monitor user numbers as ESR 52 reaches end of life (2018), continue
   security patches for XP/Vista users on ESR 52 branch if user numbers
   justify it (exact threshold TBD)

Firefox is the only major browser which still provides new releases to
Windows XP and Vista users.  Currently these two audiences represent
slightly more than 10% of our user base (XP being about 5x larger than
Vista).  By the end of 2017 the number is projected to decrease to about
half of that amount.
Microsoft ceased security updates for XP a few years ago and plans to do
the same
for Vista in early 2017.  With users no longer getting operating system
updates, it becomes increasingly difficult for those users to stay safe
online.  Further, continuing to include XP and Vista for new Firefox
releases comes at an opportunity cost (more on this below).  We are
reaching the point where we feel it is better to direct our primary efforts
to where the majority of users are (Windows 7+).

All of that said, we don't feel right about the prospect of leaving users,
who in many instances may not have the option to purchase a new computer to
update their OS, completely vulnerable due to lack of security updates.
That's why we feel that continuing to provide updates via ESR 52 (and
possible extension afterwards) allows us to reduce the opportunity cost of
supporting these OS versions, while keeping users as safe as we can.

*Opportunity Cost of Supporting Windows XP/Vista*
Continuing to release on Windows XP/Vista comes at an opportunity cost and
is becoming increasingly difficult due to our inability to source older
hardware.  By removing XP/Vista from new Firefox releases we can:

   - Lower XP/Vista specific testing/operational costs
   - Move to modern compilers
   - Simplify the codebase by removing XP/Vista-specific code from mainline
   - Avoid XP/Vista specific bugs/regressions

*What does this mean for XP/Vista users?*

   - Windows XP and Vista users will continue to get the latest Firefox
   versions up to and including v52
   - v52 will be the last version of Firefox available to XP/Vista users
   - XP/Vista users will continue to get security updates into 2018, with
   the potential for the timeframe to be extended

*How will this plan be communicated?*
Subsequent to the collection of feedback from this email, I will be
drafting a blog post describing the finalized plan.  In addition, we'll be
using some form of in-product messaging to inform users.

If you have questions/comments, please reply to the *firefox-dev* mailing


*Peter Dolanjski*
*Product Manager, Firefox*
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