
If you want to start over and wipe out the data, you need to go into Disk Utility to reformat the internal drive first, and then install macOS Sierra.Please note that before installing any system, you need to ensure there is sufficient space on your Mac. If you want to install Sierra and leave the data intact, select Install OS X. Your Mac will display an OS X Utilites window.(You don’t need to select a network to proceed.)

Click on the external drive and hit Return.

To confirm that you want to continue, type Y and hit Return. Terminal will tell you that it will erase your drive.Terminal doesn’t display characters when you type it in.


The drive will be reformatted automatically as part of the process. I’ve used different drives with success, including a VisionTek 120GB USB 3.0 Pocket Solid State Drive ($83 on Amazon) and an old 8GB Iomega Micro Mini Hard Drive.ĭon’t worry if the drive isn’t formatted for the Mac. You can use a USB flash drive or a hard drive with room for the installer software. If it automatically launches after download, quit the installer. Look for macOS Sierra in the list of apps that you’ve bought, and click on the Download button. You can download it again if you go to Purchased in the App Store. If you’ve already upgraded your Mac to Sierra, the installer is removed from the Applications folder. Keep the installer in the Applications folder.
