The most current Firefox you can run on the eol macOS 10.12, 10.13, 10.14 is Firefox 115 ESR currently at 115.15.0esr. Firefox 116.0 and later requires macOS 10.15 (ten.fifteen) or later to run.

Go to https://www.mozilla.org/firefox/all/desktop-esr/osx/, pick your language and then select Firefox 115.15.0 for download.

https://support.mozilla.org/en-US/kb/firefox-users-macos-1012-1013-1014-moving-to-extended-support

The good news is Mozilla has decided to extend support of Firefox 115 ESR updates til March 2025 and 115.21.0esr. They will decide in early 2025 if it should be extended again or not. They originally planned to stop at Firefox 115.15.0esr.

James,

Many thanks for your prompt, and most helpful, reply.

Another question: Can I just download and re-boot using 115.15.0 w/o losing or otherwise messing up the files I have saved?

Again, merci beau...

My system is already using Firefox 115 ESR currently at 115.15.0esr since 9/3/2024. Dos this mean it's as good as it's gonna be? The upgrade seemingly was down automatically. ???

See also:

• https://whattrainisitnow.com/release/?version=esr

My system is already using Firefox 115 ESR currently at 115.15.0esr since 9/3/2024. Dos this mean it's as good as it's gonna be? The upgrade seemingly was down automatically. ???

The Firefox 115.15.0esr is the current update for the older Firefox 115 ESR. If it is installed properly then it should continue to get internal updates from Mozilla until 115.21.0esr in March next year unless Mozilla extends again.