Unfortunately I do not think there is any major web browser that still supports the old EOL macOS 10.11 (ten.eleven) Firefox 116.0 and later requires macOS 10.15 (ten.fifteen) or later. https://support.mozilla.org/en-US/kb/firefox-users-macos-1012-1013-1014-moving-to-extended-support Firefox users using macOS 10.9, 10.10, 10.11 can only use Firefox 78.15.0esr as the latest update. https://support.mozilla.org/en-US/kb/firefox-mac-osx-users-esr Chrome, Chromium, Brave, Opera and such dropped macOS 10.11 back in 2022.