Perhaps you mean '''macOS''' 10.9 for Mac laptop/desktops? as iOS is the mobile OS for iPhones and older iPads before using iPadOS. Firefox for iOS (iPhone/iPad) had required iOS 13.0 at minimum for a long while as iOS 15.0 is now the minimum. In your More system details on right, your User Agent: Mozilla/5.0 (Macintosh; Intel '''Mac OS X 10.9'''; rv:78.0) Gecko/20100101 Firefox/78.0 For macOS 10.9, 10.10, 10.11 users the latest Firefox you can run is Fx 78.15.0esr as Firefox 79 to 115 requires macOS 10.12, 10.13, 10.14 at minimum to run. https://support.mozilla.org/en-US/kb/firefox-mac-osx-users-esr https://support.mozilla.org/en-US/kb/firefox-users-macos-1012-1013-1014-moving-to-extended-support In case you do not have the current 78.15.0esr https://archive.mozilla.org/pub/firefox/releases/78.15.0esr/mac/ Moved this thread to (desktop) Firefox section.