Mar 082017

Firefox ESR dark logo1.) The end is near for modern browsers on XP and Vista

After Google had stopped supporting Windows XP with Chromium 50.0 (Blink engine 537.36 & JavaScript V8 engine 5.0.71), I wondered for how much longer projects depending on it would last on the old OS. Unsurprisingly, they started dropping XP / XP x64 pretty quickly as well, like Vivaldi, Iron or the new Opera to name a few. Firefox kept support alive however, but of course, the end was looming over our (=XP users’) heads all that time, and now the decision finally has been made!

Mozilla Firefox will cease to support Windows XP, Windows XP x64 Edition and all editions of Windows Vista starting with version 53. If you’re still on 51.0.1, you’ll be provided with not just one, but two consecutive updates:


The reason for this is, that the first update just switches your update channel from “Release” to “ESR” (Extended Support Release). ESR versions are also typically present on Enterprise Linux systems like for instance RedHat Enterprise Linux 5 and 6, etc. After a quick restart, the browser will offer the real, final version for XP: Firefox 52.0 ESR.

After the update, the first thing you get to see is the notification of support ending for Windows XP and Windows Vista:

Firefox is notifying the user of how Vista & XP are no longer going to be supported

Firefox is notifying the user of how Vista & XP are no longer going to be supported (click to enlarge)

A quick check confirms it: This is now Firefox 52.0 ESR:

Firefox 52.0 ESR reporting is version

Firefox 52.0 ESR reporting is version (Click to enlarge)

According to the [Mozilla foundation], security updates will be provided for XP/Vista up until September 2017, and the actual, exact EOL date will be fixed mid-2017.

After that, there will no longer be any modern browser support for XP (NT 5.1), XP x64 & Server 2003 (NT 5.2) as well as Vista and the first edition of Server 2008 (NT 6.0). That is, unless somebody provides patched builds, but I don’t think that’s gonna happen…

2.) Electrolysis / e10s

On top of that, I have reevaluated the functionality of Mozillas’ multiprocessing technology on Windows XP x64 Edition. I tried that before with some 50.x version and failed to have Firefox spawn multiple processes for multiple tabs. This is a feature that makes Firefox more crash-proof and faster as well. I’m happy to announce that it does work with Firefox 52.0 ESR though!

Of course, this is not officially supported, not on XP / XP x64, nor on Vista. So force-enabling Electrolysis can only happen at your own risk! To enable the feature, open about:config, confirm the prompt, and then change the following properties as shown, create them manually if they don’t exist yet:

browser.tabs.remote.autostart     [boolean]   true
browser.tabs.remote.force-enable  [boolean]   true
extensions.e10sBloc­kedByAddons    [boolean]   false
extensions.e10sBloc­ksEnabling     [boolean]   false
dom.ipc.processCount              [integer]   16

You need to be a bit careful with dom.ipc.processCount however; Each Firefox process might consume hundreds of megabytes, and with that property set to 16, Firefox can spawn a total of 17 processes, 1 master process and 16 child processes (=tabs). So tune that value to something your machine can take! If you spawn to many processes on a machine with just 2GB or 4GB of memory, you might run into swapping rather quickly!

Also, you need to test this with your plugins and extensions! Not every plugin / extension will play nicely with e10s! In some cases the browser may even crash completely, or have individual tabs crash. You have been warned!

To test this, open about:support and look for Multiprocess Windows. Depending on how many browsers you have launched, it should show something like 1/1 (Enabled by user) or 2/2 (Enabled by user). Or, just open multiple tabs, load web sites in them (yes, you have to) and watch Firefox spawn additional processes in Task Manager:

Firefox spawning processes on XP x64 thanks to Electrolysis having been force-enabled

Firefox spawning processes on XP x64 thanks to Electrolysis having been force-enabled

And that’s it! Enjoy your security updates for a while longer, and then welcome Firefox into the mausoleum that is Windows XP! :) It might be the last browser you’ll ever use on that platform…

CC BY-NC-SA 4.0 The final browser for Windows XP / XP x64: Firefox 52.0 ESR (And: Electrolysis / e10s multiprocessing support) by The GAT at is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

  11 Responses to “The final browser for Windows XP / XP x64: Firefox 52.0 ESR (And: Electrolysis / e10s multiprocessing support)”

  1. well… slimjet actually works perfectly on windows xp and it is consistently updated

    • Hello gagagigo,

      I haven’t heard of Slimjet yet, but seeing as it’s based on the Chromium Engine, the most important part would be whether they can backport engine versions >=50 to XP & XP x64. E.g. Valve has frozen their Steam web component to CEF 49.0.2623.110, because newer Chromium engines wouldn’t run on XP. This has also affected the SRware Iron and Vivaldi browser projects. They all stopped supporting XP / XP x64 when Google did.

      But if the Slimjet developers are actually backporting newer engine versions, that would indeed be very interesting!

    • Hello again, gagagigo,

      It seems your statement wasn’t quite on spot. The only version of Slimjet supported on XP is an older version based on a deprecated version of the Chromium engine (50.0.2661.75).

      The current version won’t run on XP or XP x64, as I’ve just tested. It’s based on Chromium 63.0.3239.108, wich doesn’t officially support XP. So Slimjet can’t be considered a Chromium backport as far as I’m concerned. Also, the 64-bit version of based on the same modern Chromium Engine is [supposed to support XP x64], but it doesn’t actually work, see the following missing Kernel API call:

      Slimjet 17 x64 failing on XP x64
      Slimjet 17 just breaks on XP, as expected

      • yep~ the version for XP users is in fact that one (10v)
        the developer said that the slimjet 10 will receive security updates and some more things
        and that is the point because palemoon (atom version) and esr will not receive those things

        sorry if ive been somewhat brief :V

        • Alright, I see.

          I’m still a bit worried though. The last release of Slimjet 10 happened almost a year ago, so maybe the XP version is dying already? I do have to rectify my statement from above though: Slimjet 10 clearly is a Chromium backport, as its engine version 50.0.2661.75 wasn’t actually supposed to run on XP.

          As for FF ESR: Version 52 will [still be updated] up until June 2018 according to the current [lifecycle plans] (scroll down to see the image). Not much time left of course, but it’s still receiving security patches for now.

          And Palemoon? I wasn’t talking about the old Atom version, but about roytam1s’ [New Moon] backport based on current Palemoon 27 code, which is still [being maintained]. Also, roytam1 is already backporting the successor project based on FF 55 as well. It’s called the Moebius project, and the resulting web browser goes by the name of “Basilisk”. You can find the XP builds in that New Moon thread on MSFN as well.

          As for Slimjet, I’d like to give it a chance, simply for performance reasons! But I will only switch if I manage to compile it on both CentOS 6.9 Linux and FreeBSD 11.x UNIX as well, as I definitely want the same browser across all my operating systems. There is another problem though, I can’t get H.264/AVC playback to work in the context of HTML5 (like on Youtube). Do you now how to get it to play? Adobe Flash is not an option for me though:

          Slimjet 10 won't play H.264/AVC on XP
          Slimjet 10 won’t play H.264/AVC on XP? (click to enlarge)

          Anyway, thanks for pointing out Slimjet. Without that comment of yours, I might’ve never learned about that browser at all! Would be great if you have a solution for the H.264 problem in HTML5! :)

  2. I recommend using the “Process Toggle” addon to have a more user friendly way to enable multiprocess.

    And you should download and backup all your addons .xpi file, because Mozilla will remove the “legacy” XUL/XPCOM addons from their site.

    • Hello renaiv,

      Thanks for the suggestion!

      Are you saying that Mozilla will remove all .xpi files, even from all the version histories? Do you have a reliable source for that information? Because if that’s true there are quite a few people that I’d need to tell!


  3. I commented, but the thing said I didn’t enter my name and e-mail, which I did.
    Anyway, again, look in the .xpi (a zip archive), find the install.rdf and see if that extension is multiprocess capable.

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