Firefox Download For Mac 10105 Upd [hot] [Quick 2025]
Check SHA-512 hashes available in the same directory ( .checksums file) to ensure integrity.
Prevent the browser from trying to install modern updates that break stability on OS X 10.10.5: Launch Firefox. Type about:config into the navigation bar and hit enter. Accept the warning prompt to view advanced flags.
A: No, it requires macOS 10.12+. No reliable upd exists.
A window will appear showing the Firefox icon and an arrow pointing to the folder shortcut.
:Access the official Mozilla archive to download the compatible installer directly: Download Firefox 78.15.0esr (English US). firefox download for mac 10105 upd
Running Firefox 78.15 in 2026 means for Firefox-specific vulnerabilities (CVEs after Nov 2021 are unpatched). However:
: Because Firefox 78 ESR has not had security patches in years, avoid using it for sensitive tasks like online banking. Website Issues : If a site looks "broken," it might be due to Enhanced Tracking Protection . Click the shield icon
| macOS Version | Compatible Firefox Version(s) | Support Status | Key Details | | :--- | :--- | :--- | :--- | | macOS 10.12–10.14 (Sierra, High Sierra, Mojave) | | Security updates available until August 2026 | Critical security patches are provided through the Extended Support Release (ESR) channel. | | macOS 10.9–10.11 (Mavericks, Yosemite, El Capitan) | Firefox 78 ESR | Support ended (not recommended for secure browsing) | These versions are no longer secure for general use. | | macOS 10.6–10.8 (Snow Leopard, Lion, Mountain Lion) | Very old Firefox versions (pre-2016) | Support ended (not recommended for secure browsing) | Using these versions online poses significant security risks. |
: Older security certificates built into OS X 10.10.5 will throw security exceptions on HTTPS websites. Firefox uses its own internal certificate store, which helps bypass some of Safari's errors, but it can still drop connections on newer cryptographic layers. Check SHA-512 hashes available in the same directory (
According to user reports, some versions of Firefox running on macOS Catalina have experienced occasional menu-related issues, such as problems accessing settings or extension management interfaces. While Mozilla continues to address these issues in subsequent releases, most Catalina users are still able to use the browser effectively without major disruptions. If you encounter any unusual behavior, consider updating to the latest version of Firefox, as newer releases typically include bug fixes that resolve such problems.
If you find that Firefox 78 ESR cannot load the specific websites you need, your choices for staying on OS X 10.10.5 are limited. You may want to look into community-maintained legacy browsers like or Legacy Fox , which are open-source projects designed specifically to backport modern web rendering features to older Mac operating systems.
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.
– Set to 2 or 3 (same Performance panel). Accept the warning prompt to view advanced flags
Ensure that the browser does not attempt to auto-update to a modern version, as this will break the application on your system. Navigate to Firefox Preferences > General > Firefox Updates and select "Check for updates but let you choose to install them." Long-Term Alternatives for OS X 10.10.5
: Look for the file named Firefox 78.15.0esr.dmg .
Because the browser engine is frozen in time, some modern websites using cutting-edge scripts, security certificates, or CSS layouts may fail to load correctly, display formatting errors, or reject the connection entirely.
Show you where to download for 10.10.5.