How to Re-Download OS X Mountain Lion Installer from OS X Mavericks
Though it is generally recommended for users to keep their Macs up to date with the latest system software, not everyone wants to run OS X Mavericks on all of their Macs, and in some situations older Macs may not support the latest version of OS X anyway. Additionally, there are circumstances where users looking to update from Snow Leopard or OS X Lion may want to go to OS X Mountain Lion instead of Mavericks for compatibility reasons, or to avoid some of the potential issues discussed here by readers with Mail app and iCloud syncing that have frustrated some using current versions of 10.9.1 (those are since resolved with 10.9.2, update to avoid those issues). With OS X Mountain Lion officially off the App Store though, you can’t just search for it and choose to re-download, but that doesn’t necessarily mean users can’t retrieve the installer again.
Important Note: This is really a trick aimed at advanced users who know why they want an older version of OS X. Using the downloaded installer will not work to revert from a Mac with Mavericks to Mountain Lion. Users who wish to downgrade from OS X Mavericks to Mountain Lion should follow these instructions instead, but be aware that it requires a backup from the prior OS X version. If you’re experiencing unusual problems with Mavericks, you may want to try a clean install. Finally, do not attempt to install OS X Mountain Lion on a newer Mac that shipped with OS X Mavericks pre-installed, the installation of 10.8 will fail because it does not support the newest hardware while 10.9 does.
To be able to get the older version of OS X from the Mac App Store again, you must have obtained OS X Mountain Lion from the App Store at some point in time, thus tying it to your Apple ID and Mac App Store account. This works even if it was originally on another Mac than what is currently in use. If you did not buy, download, or install Mountain Lion from the App Store with an Apple ID, this will not work.
- Open the App Store application as usual, from /Applications/
- Go to the “Purchases” tab
- Scroll through the list until you find “OS X Mountain Lion” – do not use the Search box because it will try and fail by looking within the wider Mac App Store
- Click on the grey “DOWNLOAD” button
- You will find a message saying “Would you like to continue? OS X 10.9 is already installed on this computer. Are you sure you want to download OS X 10.8?” – click ‘Continue’
- Wait for the full download to complete (it’s about 5GB) and find the “Install OS X Mountain Lion” application in the /Applications/ directory
Now that you have the installer handy,you can create a boot installer for Mountain Lion if you want to perform a clean installation of 10.8 on another compatible Mac.
As mentioned before, we generally recommend keeping up to date with the latest version of OS X supported by a Mac, which for most machines is OS X Mavericks. You can build a USB installer for Mavericks
Technically, you can also re-download the OS X Lion installer this way too, though it would be hard to imagine a scenario where a user would want Lion over OS X Mountain Lion, let alone OS X Mavericks.