Find the InstallESD.dmg file inside the Contents > SharedSupport folder.Open the Application folder and find the installer app and right-click it to and choose Show package contents.

Note that I’ve not tested this procedure since the first one works so much better, but it should work fine. DIY Method for Those Wanting to Avoid 3rd Party Software This should update any system with Mountain Lion. Test the DVD or USB disk to see if the app burned the files correctly by doing the Mountain Lion update from the disk (boot the computer while the holding down the Option key).Note single layer discs won’t work and the app will erase the USB drive. Run the Lion Diskmaker and follow the app’s instructions using an 8GB USB drive or double layer DVD.Download the Mac App Store Mountain Lion install files but don’t actually update your version of OS X at this point.I recommend using the USB option since it runs the installation faster than a DVD and future Macs likely won’t ship with a DVD drive.

It finds the files and then burns them to a flash drive or DVD. Download the Mountain Lion installation files from the Mac App Sore then run the free app. The app looks for the downloaded installation files in the Application folder. The option involves downloading and installing the free app Lion Diskmaker. I recommend this easy option, but if a user doesn’t want to bother with third-party software, even if it is free and safe, then we offer a second alternative that takes a little more work.īefore performing either method of upgrading, be sure to follow our guide for getting ready for Mountain Lion. The easiest option includes installing a really simple utility. The user can also work with an SD card but that’s not recommended since some machines might not boot to an SD card. Users don’t have to download the upgrade on each system if they follow the steps below for creating a DVD or USB install disk with Mountain Lion’s upgrade installation on it. Why must I download the upgrade three times on each system? Why not download it once and then install from that download to each system.įor example, I use a MacBook Pro, MacBook Air and a Mac Mini. Apple wants users to download it on each system from their store, but that can take up precious time and bandwidth. Users can now download and install OS X 10.8 Mountain Lion from the Mac App Store.

Lion diskmaker download