You can find the specific installer on the Mozilla Release Archive.
that still receives security updates for older macOS versions? Update Firefox to the latest release - Mozilla Support
The final version of Firefox compatible with Mac OS X 10.10.5 is . Version Number: 78.15.0esr firefox download for mac 10105 upd
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. How to update outdated browser on OS X Yosemite
This can be found on GitHub by searching for "Firefox Dynasty project". Safety Tips for Using Firefox on Old Macs You can find the specific installer on the
(streaming, banking, basic browsing) If you've tried Firefox Dynasty before How to update outdated browser on OS X Yosemite
As of 2026, finding a "Firefox download for Mac 10.10.5 upd" (update) means finding the last supported version, as Mozilla has moved on to higher macOS requirements. This guide will walk you through the best, secure way to get Firefox running on your Yosemite machine. Why You Need a Specific Firefox Version for Yosemite Version Number: 78
A: The modern Firefox codebase uses APIs (Application Programming Interfaces) from macOS 10.12 Sierra and above. Modifying the binary would break core rendering.
The latest Firefox versions require . Your Mac will also need an Intel x86 or Apple Silicon processor and at least 512 MB of RAM.
To browse the web safely on OS X 10.10.5, you must use . This specific version is the final release of Firefox that retains full compatibility with Mac OS X 10.10 (Yosemite), 10.11 (El Capitan), and 10.12 (Sierra). Step-by-Step Installation Guide
Many websites will trigger connection warnings because your root security certificates on Yosemite expired years ago.