How to create a bootable USB flash drive for macOS Sierra, High Sierra, and Mojave

How to create a bootable USB flash drive for macOS Sierra, High Sierra, and Mojave

Creating a bootable macOS USB flash install drive is a great way to facilitate a clean installation of macOS.

This will work for following versions of macOS:

  1. macOS 10.12 – Sierra
  2. macOS 10.13 – High Sierra
  3. macOS 10.14 – Mojave

Before you start, you’ll need a USB 2.0 or USB 3.0 flash drive with at least 8GB of storage available. A USB-C flash drive might be better choice if you’re are a new MacBook user. 

This process will erase the contents of the flash drive, so ensure that there is nothing of importance stored on the drive that you need before starting.

Step 1

  • Open Disk Utility and format USB flash drive as Mac OS Extended.
  • Launch the App Store on your Mac.
  • Search for “macOS  Mojave” (or the current version of macOS, if different).
  • Click “Download” or “Get”.
  • If you have previously downloaded this file, you may find it in the “Purchased” tab.

Step 2

  • After the downloading process is complete, exit the App Store. The installation window should appear momentarily.
  • Click the “Install macOS Mojave” menu at the top left of the screen, and select “Quit Install macOS.

Step 3

  • Insert your USB drive into your Mac’s USB port.
  • Note the name of your USB drive – it should appear on your desktop.

Step 4

  • Launch Terminal.

    You can either use Spotlight Search or navigate to “Applications / Utilities” and double click the Terminal icon to launch Terminal.

Step 5
  • In Terminal, type one of the following commands, depending on your version of macOS. (The name of OS, is the one you want to install on the USB flash drive. Not that of your Mac’s system). These assume that the installer is still in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you’re using. If it has a different name, replace “MyVolume” accordingly. 
macOS 10.12 – Sierra
sudo /Applications/Install\ macOS\ --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\
macOS 10.13 – High Sierra
sudo /Applications/Install\ macOS\ High\ --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ High\
macOS 10.14 – Mojave
sudo /Applications/Install\ macOS\ --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\
If you did not download the file from the App Store, you must modify the file path after "applicationpath".

Step 6

  • After correctly entering the command with the name of your USB drive, press the [return] key.
  • Enter your Mac’s user password.
  • Your password will not be displayed, but it is there.
  • Press [return].
  • Check the name and path of your USB key. If it looks correct, press the [Y] key, then press [return].
  • The bootable drive creation will begin. Please wait until the process completes.

Step 7

  • When Terminal indicates the process is “Done,” the creation of your bootable drive has succeeded.
  • To boot any Mac from your USB drive, first power it off and then press and hold the [option]or [alt] (⌥) key while turning it back on.

If you get the following error when trying to reinstall macOS:

“macOS could not be installed on your computer. No packages were eligible for install. Contact the software manufacturer for assistance. Quit the installer to restart your computer and try again. “

Your date may be wrong and will need to be set correctly. Please look here for more information.

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