: If your hardware supports it, consider upgrading your OS to macOS 10.11 (El Capitan) or 10.13 (High Sierra) to use slightly newer (though still aging) browsers like Firefox 115 ESR.
If you see this error message, it typically means that Firefox is still running in the background. Open Activity Monitor (found in Applications → Utilities), search for any Firefox processes, and force quit them. Then try launching Firefox again.
On this page, you can manually select your preferred language and operating system version. This is particularly useful if you are setting up Firefox on multiple machines or need a non-default language package.
Because Firefox 78 ESR stopped receiving security updates in late 2021, it is vulnerable to modern web exploits. For a more secure experience on Yosemite, consider these alternatives: How to update outdated browser on OS X Yosemite 3 Sept 2024 —
If you found this guide helpful, please share it with others who might be facing the same issue on their older Macs! firefox download for mac 10105 upd
After successfully copying Firefox to your Applications folder, you can eject the Firefox.dmg disk image. To do this, click the eject icon next to the Firefox disk image in Finder’s sidebar, or right-click on the disk image on your desktop and select .
| Interpretation | Description | Likelihood | | :--- | :--- | :--- | | | A specific older build of the Firefox browser released in 2022. | Medium – Users often look for legacy versions for compatibility reasons. | | macOS 10.10.5 | A specific version of Apple's OS X Yosemite operating system. | High – Many searches mix Firefox and macOS version numbers. |
For users running , the most recent and final compatible version of Firefox is Firefox 78.15.0 ESR (Extended Support Release) . This version reached its final update on October 5, 2021, and is no longer receiving security patches from Mozilla. Download Instructions
Firefox 78 ESR (Extended Support Release) is generally considered the last official, stable version to work properly on macOS 10.10 Yosemite, say Reddit users . : If your hardware supports it, consider upgrading
A: Apple menu → About This Mac. Look for “Version 10.10.5”.
: Click the link above and select the .dmg file. Open the Installer : Double-click the downloaded file.
: If your browser says it is up to date but websites aren't loading correctly, it is likely because the internal certificates of version 78 are expired. Alternative Options
Modern Firefox requires macOS 10.12 (Sierra) or higher. Then try launching Firefox again
Open your folder and double-click the downloaded .dmg file.
, it remains the most functional official version for your OS. Where to Download: You can find older versions in the Mozilla release archives or through reputable community repositories like the Macintosh Repository How to Install Download the DMG: Locate the installer for Firefox 78.15.0esr. Open the File: Double-click the downloaded Drag to Applications: Drag the Firefox icon into your Applications Confirm the Version: Open Firefox, go to the top menu, and select Firefox > About Firefox to ensure you are on version 78. Critical Security Warning
| Step | Action | |------|--------| | 1 | Open archive.mozilla.org/pub/firefox/releases/ | | 2 | Click 78.15.0esr/ | | 3 | Click mac/ | | 4 | Click your language folder (e.g., en-US ) | | 5 | Download Firefox 78.15.0esr.dmg | | 6 | Install, then disable automatic updates | | 7 | Enjoy the latest possible update for Mac 10.10.5 |