Hello, Using an older version will cause security issues. There are ESR versions that keep security updates, but stay at an older feature version. See [[Switch to Firefox Extended Support Release (ESR) for personal use]] for more details. If you must use an older version without stability and security updates, see [[Install an older version of Firefox]]

''<p>philip.chassler [[#question-1361441|said]]</p>'' <blockquote>I have a MacBook Pro with system 10.11.6, but I replaced, I assumed it would work because there was no indication otherwise, it with the newest Firefox version, turns out my system cannot accommodate it--can you send me a link to the older Firefox? Thanks. </blockquote> Firefox 79.0 and later has required MacOS 10.'''12''' at minimum to run so you will need to upgrade to MacOS 10.'''12''' or higher to use any more current version of Firefox. https://support.mozilla.org/en-US/kb/firefox-mac-osx-users-esr https://www.mozilla.org/firefox/78.0/system-requirements/ https://www.mozilla.org/firefox/79.0/system-requirements/ https://www.mozilla.org/firefox/95.0/system-requirements/ Fx '''78.15.0'''esr is the most current version you can use though it is EOL with no more updates. https://archive.mozilla.org/pub/firefox/releases/78.15.0esr/mac/en-US/ other locales at https://archive.mozilla.org/pub/firefox/releases/78.15.0esr/mac/

''<p>andmagdo [[#answer-1467047|said]]</p>'' <blockquote>There are ESR versions that keep security updates, but stay at an older feature version. See [[Switch to Firefox Extended Support Release (ESR) for personal use]] for more details. </blockquote> The Firefox 91.0.x ESR will not work.

Thank you James, I have not looked into this very far.