How to do a clean install of mac os sierra install#
When your Mac’s startup disk is formatted, return to the Utilities window and select “Install macOS”, choose your freshly erased startup drive when asked where to install the OS, and follow the onscreen prompts to complete the installation. Once the USB drive has booted, select “Disk Utility” from the Utilities window, choose your Mac’s startup drive from the list, and click “Erase”.ģ. Use the mouse pointer or the arrow keys on your keyboard to select the disk called “Install macOS Sierra” in the drive list that appears on the screen.Ģ. Once the USB installer has been created, restart your Mac and hold down the Option key as soon as you hear the reboot tone. The process will take a few minutes to complete, so leave it running. Enter it, and the command will create a bootable Sierra installer on the USB drive. You should be prompted for your administrator password. Now, ensure the USB drive is the only disk named “Untitled” connected to your Mac, and then paste the following command into the Terminal window, and press Enter: sudo /Applications/Install\ macOS\ “macOS Sierra.app”/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ macOS\ “macOS Sierra.app” –nointeractionĤ. Once your thumb drive is formatted and the macOS installation package has finished downloading, open up Terminal (found in Applications/Utilities).ģ. Name the USB drive “Untitled” if it isn’t already, choose the Format “OS X Extended (Journaled)”, and click “Erase”. Open Disk Utility (found in the Applications/Utilities folder), select the thumb drive in the sidebar and click the “Erase” button.Ģ. Once it has downloaded, follow these steps to create a USB bootable installer.ġ. Now that we’ve considered the question of whether or not to do a clean install, here’s how you can do a clean install of macOS Sierra (courtesy of MacRumors):ĭownload the macOS Sierra installation package from the Mac App Store. How to do a clean install of macOS Sierra Before doing a clean install, make sure you backup all of your data.