How to Create a Bootable macOS High Sierra USB Installer
Like its predecessors, users can upgrade to macOS High Sierra via the Mac App Store. For most users, this is the easiest and simplest way to upgrade to Apple’s latest Mac operating system. But sometimes it’s nice to have a bootable macOS High Sierra USB installer, which lets you install High Sierra from scratch on a new or wiped drive, troubleshoot installation issues, or save time and bandwidth if you need to upgrade multiple Macs.
The bad news is that Apple no longer distributes macOS physically via an installer DVD. The good news, however, is that users can easily create their own bootable macOS High Sierra USB installer with just a few quick steps. Here’s how to do it.
Note: macOS High Sierra is currently in beta. The instructions below cover how to create a bootable High Sierra installer for this beta, and will not work without modification on the final public release. We will update this article when macOS High Sierra is publicly released later this year.
Step 1: Download macOS High Sierra from the Mac App Store
The first step to create your own bootable macOS High Sierra USB installer is to download the app-based installer Apple provides via the Mac App Store. For the current beta, users will find High Sierra in their Purchased tab after registering their Mac. When High Sierra is finally released, you’ll be able to find it linked in the sidebar of the Mac App Store homepage.
The macOS High Sierra download is relatively large at just over 5GB, so it may take some time to download depending on the speed of your Internet connection. Once it’s done, the High Sierra installer app will automatically launch.
This app is how you would normally upgrade your Mac, but we don’t need to run it now for the purposes of creating our bootable USB installer. Therefore, close the installer app by pressing Command-Q on your keyboard.
Step 2: Prepare Your USB Drive
To create a bootable macOS High Sierra USB installer, you need a USB 2.0 or USB 3.0 drive with a capacity of at least 8GB. Creating the installer will erase all data on the USB drive, so make sure to back up any existing data that may be on the drive.
Plug the USB drive into your Mac and launch the Disk Utility app. You can find Disk Utility by searching for it in Spotlight or in the Applications > Utilities folder.
In Disk Utility, select your USB drive from the list on the left. Next, click Erase from the toolbar. We need to give the USB installer a temporary name in order for the Terminal command below to work. If you plan to just copy and paste the Terminal command, name your USB drive “HighSierra.” You’re free to change it, but you’ll need to modify the command to reference the new name.
Ensure that the “Format” drop-down is set to Mac OS Extended (Journaled) and that “Scheme” is set to GUID Partition Map. When you’re ready, click Erase to wipe the drive.
Step 3: Create the Bootable macOS High Sierra USB Installer
Once your USB drive is erased, launch the Terminal app (located by default in the Applications > Utilities folder). Copy and paste the following command into the Terminal window and press Return on your keyboard to execute it:
sudo /Applications/Install macOS 10.13 Beta.app/Contents/Resources/createinstallmedia –volume /Volumes/HighSierra –applicationpath /Applications/Install macOS 10.13 Beta.app –nointeraction
This is a sudo command, so you’ll need to enter your admin password when prompted. Terminal will then access the createinstallmedia tool built in to the High Sierra installation bundle. You can monitor the progress of the process via the Terminal window.
The time it takes to complete the creation process will vary based on the speed of your USB drive. In most cases, it shouldn’t take more than 5 minutes. Once the process is complete, you’ll see the Terminal window display “Done.”
Your new bootable macOS High Sierra USB Installer will now mount to your Mac, ready for use.
Step 4: Install macOS High Sierra via USB
Once you have your bootable macOS High Sierra USB installer, you can use it to install High Sierra on compatible Macs in one of two ways. First, you can connect it to a running Mac and launch the upgrade installer. This will produce the same result as upgrading via the Mac App Store, but it saves you from having to download the High Sierra installer application first.
Second, you can use your USB drive to perform a clean install of High Sierra. To do so, first power off the Mac you wish to upgrade and plug in your USB drive. Next, hit the Mac’s power button to turn it on and then press and hold the Alt/Option key on your keyboard as soon as you hear the Mac’s startup chime.
Keep holding Alt/Option until you see the Startup Manager appear. Use the cursor or the arrow keys on your keyboard to select your bootable High Sierra USB installer. The Mac will now boot to the High Sierra installer and, because it is running off of the USB drive, it can access and erase your Mac’s internal drive. Once erased, the installer will perform a clean install of High Sierra on your drive (just make sure to back up before performing a clean install!).