Moved thread from Firefox for iOS (for iPhone/iPad) as you have Mac OS. According to your Question Details > More system details you appear to have Mac OS X 10.11 (ten.eleven) Mozilla/5.0 (Macintosh; Intel '''Mac OS X 10.11'''; rv:78.0) Gecko/20100101 Firefox/78.0 Firefox since 79.0 and later including current has required macOS 10.'''12''' (ten.twelve) at minimum to run. The most current you can run on Mac OS X 10.9, 10.10, 10.11 is Firefox '''78.15.0''' esr (78.fifteen.0) as the 78.2.0 esr (78.two.0) you posted is older. https://archive.mozilla.org/pub/firefox/releases/78.15.0esr/mac/en-US/ other language locales are at https://archive.mozilla.org/pub/firefox/releases/78.15.0esr/mac/en-US/ https://support.mozilla.org/en-US/kb/firefox-mac-osx-users-esr