Select the USB drive and let it do it's thing.Ī few choices will come up in a moment. You'll be given an option to select a boot drive/partition. Restart computer and hold down the 'Option' key as it goes through the boot process. Make a bootable backup on a 16GB flash drive You want the installer unused and located in your applications folder. If it begins automatically simply cancel. You can now make your bootable backup.Īnyway, I'm an upgrade from ML so I re-downloaded the Mavericks installer and here's the very short version of how it works.Īfter downloading Mavericks do NOT install. Although another option would be to use your other Mac to re-download Mavericks then simply copy the installer to the Air, putting it into your applications folder (but don't run it). If Mavericks came already installed then you'll have to use the disc that came with it. Using the recovery partition doesn't work for a lot of people.Īlso, how old is your Air? Did it come pre-installed with Mavericks or did you upgrade from ML? If you upgraded simply re-download Mavericks from the App store (free). Finally tried the simplest method that most users said didn't work use a bootable USB flash installer if you've made one. I don't know if you've resolved your problem yet but I was getting the same error message when trying to format a 1T external drive.ĭid some research today and after about 20 different suggestions I tried a few with no joy.

Macbook air disk utility boot