Mac 10105 Upd | Firefox Download For

| Firefox Version | macOS 10.10.5 | Security Updates | |----------------|---------------|------------------| | Firefox 78 ESR | ✅ Yes | ❌ No (EOL) | | Firefox 79+ | ❌ No | N/A |

Since this is an older build, macOS might block it due to an expired gatekeeper ticket. If you see the warning “Firefox can’t be opened because it was not downloaded from the App Store”:

Download Firefox for Mac OS X 10.10.5 (Yosemite)

If you're using Mac OS X version 10.10.5 (Yosemite), you can still run an older but stable version of Firefox that is compatible with your system.

Important Note:
The latest versions of Firefox no longer support OS X 10.10.5. The last compatible release is Firefox 78 ESR (Extended Support Release), which includes security updates until November 2021.

Steps to Download Firefox 78 ESR for OS X 10.10.5:

Direct download link (official Mozilla source):
https://ftp.mozilla.org/pub/firefox/releases/78.15.0esr/mac/en-US/

Note: After installation, it's recommended to avoid updating to newer versions, as they will not work on OS X 10.10.5.

Keeping Yosemite Alive: How to Download Firefox for Mac 10.10.5

If you’re still rocking a Mac with OS X Yosemite (10.10.5), you know the struggle. Modern websites are heavy, and Safari 8 feels like it's trying to run a marathon in flip-flops. You need a browser that still respects your hardware while letting you actually check your email.

Enter Firefox. While Mozilla has officially moved on to newer versions of macOS, you can still get a functional, stable version of Firefox for your Yosemite machine. Here is everything you need to know to get back online. The Best Version for Yosemite: Firefox 78 ESR

For users on Mac OS X 10.9, 10.10, and 10.11, the "end of the road" was Firefox version 78 Extended Support Release (ESR). firefox download for mac 10105 upd

Why this version? It was the last major release to officially support Yosemite.

Is it safe? It received its final security update (version 78.15.0esr) on October 5, 2021. While it's more secure than the outdated version of Safari that comes with Yosemite, it no longer receives active patches. Step-by-Step: How to Download and Install

Since the main Firefox Download Page will likely try to give you the newest version (which won't open on your Mac), you need to grab the specific legacy installer.

Get the Installer: Navigate to the Mozilla Support Page for Legacy Mac Users or search for the Firefox 78.15.0esr dmg directly.

Open the DMG: Once the download finishes, double-click the Firefox 78.15.0esr.dmg file.

Install: Drag the Firefox icon into your Applications folder.

Launch: Open your Applications folder and double-click Firefox. You might see a warning that it was "downloaded from the internet"—just click Open. Pro Tips for Older Macs Browser Suggestions for Old Mac Laptop Yosemite 10.10.5

Report: Firefox Support for macOS 10.10.5 (Yosemite) Executive Summary

Mozilla Firefox no longer officially supports macOS 10.10.5 (Yosemite) with its current releases. The final official version compatible with this operating system is Firefox 78.15.0esr (Extended Support Release)

. Users remaining on this legacy OS face significant security risks as this version ceased receiving critical security updates in October 2021. Technical Findings Last Compatible Version

: Firefox 78.15.0esr is the terminal build for macOS versions 10.9 through 10.11. Security Status | Firefox Version | macOS 10

: End-of-life. No further security patches or feature updates are provided, leaving the browser vulnerable to modern exploits. Modern Compatibility

: Current mainstream versions of Firefox (e.g., Firefox 130.0+) require macOS 10.15 (Catalina) or later. Download Resources

For users who must maintain a legacy Yosemite environment, installers can still be sourced from historical archives: How to update outdated browser on OS X Yosemite

It looks like you’re trying to find a Firefox download for Mac OS X 10.10.5 (Yosemite).

However, the latest versions of Firefox no longer support OS X 10.10.5. Mozilla ended support for 10.10, 10.11, and 10.12 after Firefox 78 (ESR) and Firefox 79+.

Here’s what you can do:

  • Or download from Mozilla’s official “Firefox for older Macs” page:

  • Note: Using Firefox 78 ESR means no new features, and security updates ended in 2021. For better security, consider updating macOS (if your Mac supports it) or switching to a lightweight browser like Pale Moon or Arctic Fox (community-maintained for older macOS).

    • If you meant macOS 10.15 (Catalina) instead of 10.10.5, let me know and I’ll give you the latest compatible Firefox link.

    If you are looking to download Firefox for Mac OS X 10.10.5 (Yosemite), you have likely noticed that the latest versions of Firefox no longer support this operating system. Because Mozilla ended support for Yosemite in late 2021, you cannot simply download the standard "latest" version from the main Firefox website.

    Instead, the most recent and secure version available for your system is Firefox 78.15.0 ESR (Extended Support Release). Why You Need a Specific Version Since this is an older build, macOS might

    Modern browsers require newer system libraries that Yosemite lacks. If you try to run the current Firefox release, it will either refuse to install or crash upon opening. Firefox 78 ESR was the final version branch to support macOS 10.9 through 10.11. How to Download Firefox for Mac 10.10.5

    To get the correct version, you must access Mozilla’s archives. Follow these steps to ensure you are downloading from a legitimate source:

    Visit the Official Archive: Go to the Mozilla CDN Directory for version 78.15.0esr.

    Download the DMG: Look for the file named Firefox 78.15.0esr.dmg.

    Install: Open the DMG file and drag the Firefox icon into your Applications folder.

    First Launch: When you first open it, macOS may warn you that it’s an application downloaded from the internet. Click Open to proceed. Key Considerations and Risks

    While version 78.15.0 ESR is the "best" choice for Yosemite, there are important caveats to keep in mind:

    Security Risks: This version received its final security update on October 5, 2021. It is now several years out of date and does not protect against modern web vulnerabilities.

    Website Compatibility: Many modern websites (like banking or high-security portals) may not load correctly or may flag your browser as "too old".

    Performance: Newer web technologies like advanced CSS or video codecs may run slowly or not at all on this legacy version. Can You Update Further? Firefox 78.0, See All New Features, Updates and Fixes

    Solution: Firefox 78 ESR cannot read profiles from Firefox 90+. Create a fresh profile:
    /Applications/Firefox.app/Contents/MacOS/firefox-bin -P

    Safari on Yosemite is outdated – many modern websites (banking, streaming, cloud apps) break. Chrome dropped support for 10.10.5 years ago. Firefox ESR remains the only modern, secure browser for these legacy Macs (MacBook Air 2011, Mac mini 2012, iMac Late 2009, etc.).

    Key benefits of the final Firefox for 10.10.5: