Mozilla announced on December 23, 2016 that it will support the Windows operating systems XP and Vista at least until September 2017.
The organization announced back in September 2016 that it plans to make Firefox 52 the latest major version of the browser that supports Windows XP and Windows Vista.
Firefox 52 will be released on March 7, 2017 according to the browser's release schedule. Mozilla plans to move all XP and Vista users of the web browser to the Firefox Extended Release Channel (ESR) in March.
The move ensures continued support for the operating systems at least until September 2017 according to Mozilla. The organization will reassess the number of XP and Vista users in mid-2017 and use it to decide on a final end of release date for Firefox on those two operating systems.
While that end of support date is still undecided, it will be between September 2017 and mid-2018 as Firefox 52 ESR will be moved to Firefox 59 ESR by that time, and that new version won't support XP or Vista.
Firefox ESR is a special release of Firefox for organizations who require long term support and don't want to or can't test new Firefox releases every six weeks or so.
Mozilla plans to implement changers to the Firefox (non ESR) installer to block the installation of the browser on Windows XP and Vista machines. It has yet to be seen how portable versions of Firefox will handle execution on unsupported machines, and how Mozilla will handle non-production versions of Firefox on XP or Vista.
According to the Firefox Hardware Report, Windows XP accounts for 10.36% and Windows Vista for 2.56% of all systems reporting metrics back to Mozilla. That's still almost 13% of the browser's user base in total.
While Mozilla continued to support Firefox for XP and Vista, Google did drop support already in its Chrome web browser in mid-2016. Of all major browser makers, only Opera and Mozilla are still supporting XP and Vista.
Microsoft did end support for the then-and-still popular operating system Windows XP back in April 2014, and will drop support for Windows Vista in April 2017.
The decision to end support for XP and Vista leaves users on these operating systems in a predicament. The operating system itself is no longer support -- or won't be come April 2017 -- and now the browser will also stop receiving security updates eventually.
Users may stick with an unsupported version of Firefox, e.g. the last Firefox 52 ESR release that supports XP or Vista. Other options are to use virtualization to run other browsers, or to switch to another operating system entirely. There is always Linux, and it is free to install and use.
Now You: are you affected by the end of support announcement?