For users on legacy operating systems like Yosemite, Mozilla provides a special branch called ESR (Extended Support Release). Unlike the standard consumer version that updates every four weeks, ESR focuses on stability and security patches for enterprise users—and incidentally, for old Macs.
Key details of Firefox 78 ESR for Mac 10.10.5:
The firefox download for mac 10105 upd is a very specific necessity. By downloading Firefox 78.15.0 ESR directly from Mozilla’s FTP server, you can breathe another year or two of life into your Mac running OS X Yosemite 10.10.5.
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.
Download Link Summary:
If this guide helped you, consider donating your old Mac to a school or recycling it properly. Legacy software can only patch security holes for so long.
For users still running macOS 10.10.5 (Yosemite), the final supported version of Firefox is Firefox 78.15.0 ESR (Extended Support Release).
Because modern versions of Firefox (version 79 and later) require macOS 10.12 or newer, you must manually download the legacy installer to maintain functionality on Yosemite. Download and Installation Guide Locate the Legacy Installer:
Navigate to the official Mozilla FTP archive or the Mozilla Support page for legacy systems . Download the file named Firefox 78.15.0esr.dmg. Install the Application: Open the downloaded .dmg file from your Downloads folder. Drag the Firefox icon into your Applications folder. firefox download for mac 10105 upd
If prompted to replace an existing version, select "Replace" to ensure the older, compatible version is installed. Bypassing Security Warnings:
Upon first launch, you may see a warning that the app was downloaded from the internet. Click Open.
If macOS prevents the app from opening, go to System Preferences > Security & Privacy > General and click Open Anyway. Critical Support Information How to update outdated browser on OS X Yosemite
For users running macOS 10.10.5 (Yosemite), the latest and final compatible version of Firefox is Firefox 78.15.0esr. Summary of Support
Modern versions of Firefox no longer support macOS 10.10. Support for this operating system officially ended on October 5, 2021.
Final Version: Firefox 78.15.0esr (Extended Support Release).
Current Status: This version no longer receives security updates from Mozilla. How to Download
Since the standard Firefox Download Page will typically offer the newest version (which requires macOS 10.15 or later), you must manually download the legacy installer. For users on legacy operating systems like Yosemite,
Official Mozilla Archive: You can find older versions via the Mozilla Support Forum or directly from the Mozilla FTP Archive.
Third-Party Repositories: Sites like Uptodown and MacUpdate maintain archives of older .dmg files if the official archive is difficult to navigate. Recommendations for Older Macs
Running an outdated browser on an unsupported OS poses security risks. To use the latest version of Firefox:
Check for OS Updates: See if your Mac can be updated to at least macOS 10.15 (Catalina) or higher.
Use Safari for Downloads: If your current browser is struggling to load modern HTTPS websites, use the native Apple Safari to download the Firefox installer.
Alternative Browsers: If Firefox 78 does not meet your needs, some users on legacy macOS versions look toward community-maintained browsers like Pale Moon or SeaMonkey, though compatibility varies.
⚠️ Recommendation: If possible, upgrade macOS or use a lightweight modern browser like Chromium Legacy or Waterfox Classic.
Running Firefox 78.15 in 2026 means no new security patches for Firefox-specific vulnerabilities (CVEs after Nov 2021 are unpatched). However: If this guide helped you, consider donating your
Firefox download for mac 10105 upd gives you the best available browser, but not a perfect shield.
Mozilla no longer links old versions directly. Use the official archive:
🔗 Mozilla FTP directory (safe, official):
https://ftp.mozilla.org/pub/firefox/releases/78.15.0esr/mac/
Steps:
✅ Checksum verification (optional but recommended):
Download the file:
Firefox 78.15.0esr.dmg (size ~85 MB).
You cannot get this version through the standard "Download Firefox" button on the main Mozilla page (that will give you an error saying your OS is too old).
Follow these steps to get the correct version: