Version: Updating from OS X 10.5 or Earlier

1
Make sure your Mac can run OS X 10.6. You can't update Safari on OS X 10.5 (Leopard) or earlier, so you'll need to upgrade to at least OS X 10.6, which means your Mac must have at least one gigabyte of RAM. You can verify this requirement by clicking the Apple icon in the top-left corner of the screen, clicking About This Mac, and looking at the number next to "Memory".
2
Purchase a copy of Mac OS X 10.6 (Snow Leopard). You can buy a hard copy from Apple's store (http://www.apple.com/shop/product/MC573Z/A/mac-os-x-106-snow-leopard), or you can search for "Mac OS X Snow Leopard" on Amazon.
- Snow Leopard is the first rendition of OS X to run the Apple App Store, which is necessary to update to newer operating systems such as Yosemite or MacOS. You can also use the App Store to update Safari.
3
Install OS X 10.6 on your Mac. To do so, insert the Snow Leopard CD into your Mac's CD slot (it's on the left side of the Mac's housing) and follow the on-screen instructions.
- You will have to restart your Mac during the installation process.
4
Click the Apple Menu icon. It's an apple-shaped icon in the top-left corner of the screen.
5
Click Software Update. After a moment, you'll see a window pop up with several update options.
6
Make sure the "Safari" box is checked. You can elect to update to a newer version of OS X (e.g., Yosemite) from this window as well, though doing so will take some time.
7
Click Install [number] Items. This button is in the bottom-right corner of the "Update" window. Doing so will install each item next to which you placed a checkmark.
8
Wait for the updates to finish installing. You may need to restart your computer during this process. Once the installation is complete, your Mac's version of Safari should be up-to-date for OS X 10.6, and you should no longer encounter error messages when attempting to access pages or software in Safari.

Version: Updating from 10.6 or Later

1
Open your Mac's App Store. It's the blue app with a white "A" on it; you should see this option in the dock.
- If you don't see the App Store, click the magnifying glass in the top-right corner of the screen and type "App Store" into the search field, then click the "App Store" result.
2
Click the Updates tab. You'll see this option on the far-right side of the row of options at the top of the App Store window.
3
Click Update right of the "Safari" option. Doing so will prompt Safari to update to the latest supported version.
4
Ensure that automatic updates are enabled. You can make sure that you're always running the latest version of Safari by checking that automatic updates are enabled:
- Click the Apple menu and select System Preferences.
- Click the App Store option in the System Preferences menu.
- Check the "Automatically check for updates" box.
- Check the boxes to enable automatic app and system updates.

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