During a recent AMA session on Reddit, Mozilla engineers revealed that the company plans to extend Firefox support on old, now-unsupported operating systems, such as Windows 7, 8, 8.1, and macOS 10.12-10.14.
Mozilla did not reveal any specific timeframes, but now, it appears we have more information on that.
According to the Firefox Release Calendar website, Firefox 115 ESR, the latest Firefox version with support for Windows 7, 8, and 8.1, will continue receiving updates until April 1, 2025. Firefox 115.21 ESR is expected on March 4, 2024, which means users with old Windows versions have at least seven more months of support from Firefox.
Initially, Mozilla planned to ditch Windows 7-8.1 support in September 2024 but changed its plans. Now, Mozilla offers two ESR releases: 115 for unsupported operating systems and 128 for Windows 10 and newer. Removing Windows 7 support from Firefox 116 and onward allowed Mozilla to clean up the code base and removed the burden of maintaining newer libraries that no longer support pre-Windows 10 releases. At the same time, Mozilla says there are enough Firefox users on Windows 7, which justifies the extended support:
Continuing to support it past October isn't going to be free (backporting security fixes is already getting increasingly painful due to the divergence which naturally happens over time as an ESR goes further into its lifecycle), but there's still enough users there that we felt it was worth doing for now at least.
According to a comment from a Firefox engineer, Mozilla "expects to have more official communications about it in the near future."
For reference, Microsoft, Google, and other browsers stopped updating their browsers all the way back in January 2023. The end of Chromium support on Windows 7, 8, and 8.1 forced other developers, such as Valve and its Steam, to stop updating their software as well.