Hmm normally you could go to https://www.mozilla.org/firefox/all/desktop-esr/win/ then pick your language then download the 32-bit Firefox 115.16.0esr.exe. (https://www.mozilla.org/firefox/all/)

However it seems like they are not serving Firefox 115 ESR there anymore like they did with 115.15.0esr and earlier even though Firefox 115 ESR is now being supported till 115.21.0esr in March 2025 at minimum.

Here is an alternative way to download the 32-bit Firefox Setup 115.16.0esr.exe https://archive.mozilla.org/pub/firefox/releases/115.16.0esr/win32/en-US/ other language locales https://archive.mozilla.org/pub/firefox/releases/115.16.0esr/win32/

If you go to https://www.mozilla.org/en-US/firefox/windows/ while using Firefox on WIndows 7, 8, 8.1 then you may then be able to download Firefox 115.16.0esr. However your Firefox UserAgent of Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:109.0) Gecko/20100101 Firefox/115.0 may have the site serve you 64-bit Firefox instead of 32-bit.

Also if you were to use Firefox 115.15.0esr or later on Windows 10/11 then it may try to update you to Firefox 128 ESr and not serve you Fx 115 ESR updates.

Many thanks for your help.

I found the easiest way was your second option in the first post. I seems to have worked fine.

Why Mozilla have chosen to reject those of us still needing the older Windows support I can understand to an extent but it just makes life a little more insecure.

Once again many thanks.

115 will be maintained until next April. It seems a bit odd that after putting that effort in they make it so hard to find.