Disclaimer: Using unpatched browsers on older operating systems carries inherent security risks. Always back up your data. If you'd like, I can: Tell you directly.
Modern Firefox requires macOS 10.12 (Sierra) or higher.
: Current mainstream versions of Firefox (e.g., Firefox 130.0+) require macOS 10.15 (Catalina) or later. Download Resources firefox download for mac 10105 upd
Look for the file named:
While this setup is not recommended for primary, secure daily driving, it is the best possible modern browsing experience available for your legacy hardware. Keep your expectations realistic, use a robust ad-blocker, and consider upgrading your machine at the earliest opportunity. Modern Firefox requires macOS 10
Since the automatic updater in Firefox may not work correctly on such an old OS, you need to download the final supported version directly.
Firefox Download for Mac 10.10.5 (OS X Yosemite): Legacy Setup Guide Keep your expectations realistic, use a robust ad-blocker,
If your Mac hardware supports it, the best "update" isn't a new browser—it’s a new OS.