Starting with Firefox version 49, Firefox requires Mac OS X 10.9 (Mavericks) or higher. Visit this Apple Support page to find your Mac OS version.

If you're using an outdated version of Firefox on Mac OS X 10.8 (Mountain Lion) or earlier, the only way you can update Firefox to a secure version is to upgrade your Mac OS to a version that Apple supports. Visit this Apple Support page to learn more about upgrading your Mac.

Open that app from your Applications folder to begin installing the operating system. MacOS Sierra 10.12 can upgrade El Capitan, Yosemite, Mavericks, Mountain Lion, or Lion; OS X El Capitan 10.11 can upgrade Yosemite, Mavericks, Mountain Lion, Lion, or Snow Leopard; OS X Yosemite 10.10 can upgrade Mavericks, Mountain Lion, Lion, or Snow Leopard. Download El Capitan: High Sierra: METHOD: How to upgrade from L. Download OS X El Capitan. For the strongest security and latest features, find out whether you can upgrade to macOS Catalina, the latest version of macOS. If you still need OS X El Capitan, use this link: Download OS X El Capitan. A file named InstallMacOSX.dmg will download to your Mac. Install the macOS installer Mac Os Lion Iso Download.

Os X Mountain Lion To El Capitan Drive

El Capitan is the twelfth major release (version 10.11) to the Macintosh operating system. It is the successor to the Yosemite and Apple has added new features and a few improvements to this version. OS X Mountain Lion (version 10.8) is the ninth major release of macOS, Apple Inc.' S desktop and server operating system for Macintosh computers.

While insecure versions of Firefox will continue to work on OS X 10.8 and earlier, using an up-to-date version of Firefox on a supported version of Mac OS will provide you with the best and safest user experience.

Operating system upgrades bring increases in efficiency, new features, stronger security, and updates to included software utilities. The following page shows you how to upgrade your Apple Macintosh desktop or laptop computer to Catalina (10.15), the current version of macOS.

• Check compatibility.

Check compatibility

Before installing Catalina, verify your Mac is eligible for the upgrade.

Verify the model of your Mac

The following Mac models can be upgraded to macOS Catalina.

• Mac Pro - All models produced from mid-2013 and later.
• MacBook Pro - All models produced from mid-2012 and later.
• iMac - All models produced from late 2012 and later.
• MacBook - All models produced from late-2015 and later.
• MacBook Air - All models produced from late-2012 and later.
• Mac mini - All models from mid-2012 or later.

If your Mac is not on this list, you cannot upgrade to Catalina. However, you can still try to upgrade to El Capitan.

Back up your data

Although not required, we strongly recommend you back up your Mac before proceeding with an upgrade. If anything goes wrong, you can restore your Mac to its previous state.

Check your OS version

The following versions of OS X and macOS can be upgraded to macOS Catalina.

OS name	Version	Release date
OS X Lion*	10.7	July 20, 2011
OS X Mountain Lion*	10.8	July 25, 2012
OS X Mavericks	10.9	October 22, 2013
OS X Yosemite	10.10	October 16, 2014
OS X El Capitan	10.11	June 8, 2015
macOS Sierra	10.12	June 13, 2016
macOS High Sierra	10.13	June 5, 2017
macOS Mojave	10.14	June 4, 2018

* If your Mac is running OS X Lion or Mountain Lion, you must upgrade to El Capitan before you can upgrade to Catalina.

If your Mac is running Mavericks or newer, you can proceed to upgrade to Catalina.

How To Upgrade Macos Mountain Lion To El Capitan

Upgrade to El Capitan, if necessary

If your Mac is running OS X Lion or Mountain Lion, follow these steps to upgrade to El Capitan.

1. Download the El Capitan installer from Apple. The file size is 5.8 GB, so the download may take a while, depending on the speed of your Internet connection.
2. Double-click the downloaded archive, InstallMacOSX.dmg, to view its contents.
3. In the archive, double-click InstallMacOSX.pkg.
4. Follow the on-screen instructions to perform a compatibility check, and prepare for installation.
5. When this process is complete, an installer application named Install OS X El Capitan is placed in your Applications folder. Double-click it to begin installation.
6. During installation, your Mac may restart, or display a blank screen short time. Do not close the lid or power off your Mac until installation is complete.

Upgrade to Catalina

Os X Mountain Lion Free Download

After you've gone through the preparation steps, you need to download and install the latest version of macOS. The following steps show you how.

Os X Mountain Lion Vs El Capitan

1. In the menu bar, click the Apple icon to open the Apple menu.
2. In the Apple menu, select App Store.

3. In the App Store, on the left side of the window, select Updates.

Mac Os Mountain Lion Vs El Capitan

4. In the Updates window, locate the line that says Catalina.
5. On the far right side, select Update.
6. Catalina is downloaded and installed.
7. During installation, your Mac may restart, or display a blank screen for a short time. Do not close the lid or power off your Mac until installation is complete.

Additional information

• See our update definition for further information and related links.