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How to make macOS Big Sur Beta Bootable USB Install Drive

How to make a macOS Big Sur beta installer

Advanced Mac users will often create a boot disk installer for macOS Big Sur beta so that something like a USB flash drive can be used to boot and install macOS Big Sur on any compatible Mac.

Bootable MacOS installation USB drives provide the ability to clean install macOS Big Sur, update to macOS Big Sur, install macOS Big Sur beta on multiple Macs without downloading the installer, and the ability to use Disk Utility to partition and delete a machine, perform Time Machine restorations and more.

If you are interested in creating a MacOS Big Sur bootable USB installation drive, this tutorial will go through that process.

Requirements to create a boot macOS Big Sur USB Install Drive

To create a bootable macOS Big Sur beta installer, you need the following:

If you have not already downloaded the macOS Big Sur beta installer, you need to do so before starting the process, which means you also need an internet connection.

The rest of the process of creating a macOS Big Sur (macOS 11 aka macOS 10.16) USB installation drive involves the terminal. This means that this process is most appropriate for advanced users with an understanding of the command line. Improper use of the command line in this process can lead to permanent data loss by deleting the wrong disk. If you are not sure about the features, back up your Mac before you begin.

How to make a bootable macOS Big Sur Beta USB installation drive

Be sure to use precise syntax on the command line, otherwise failing to do so may result in permanent data loss. Continue at your own risk.

  1. Connect the USB flash drive to the Mac you want to convert to the bootable macOS Big Sur installer by naming the drive “UNTITLED” *
  2. Open the “Terminal” application via Spotlight by pressing Command + Spacebar and typing Terminal and pressing the return key, through the Launchpad, or via the Tools folder in the Finder
  3. Enter the command on the Terminal command line that corresponds to the version of macOS Big Sur beta you have (versions have different application installation names), provided that “UNTITLED” is the name of the USB flash drive that can be converted to a bootable macOS Big Sur installation drive:
  4. MacOS Big Sur public beta
    sudo /Applications/Install macOS Big Sur Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/UNTITLED --nointeraction

    MacOS Big Sur Beta 2 and later
    sudo /Applications/Install macOS 11 Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/UNTITLED --nointeraction

    MacOS Big Sur Developer Beta 1
    sudo /Applications/Install macOS Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/UNTITLED

  5. Double-check that the syntax is correct and the volume is specified correctly, then press the return / enter key and enter the admin password to start the startup program creation process **

Let the process complete, it may take some time depending on the speed of the Mac, the speed of the USB flash drive used and other variables. When completed, the terminal will report a “Done” message.

Once the macOS Big Sur 11.0 USB bootable installation drive has been successfully created, it will be automatically mounted on the Mac and ready for use.

At this point, you can use the bootable installation drive macOS Big Sur beta, just like any other boot disk or installation drive on any other macOS Big Sur compatible Mac.

* You can name the USB flash drive something else, but the syntax as written is intended or a drive called UNTITLED (which is the default for a newly formatted drive through Disk Utility).

** If a “command not found” error message appears on the command line, it is probably due to a syntax error, or because “Install macOS Beta.app” is not found in the application folder as expected. Double-check the syntax for typos, and make sure the macOS Big Sur beta installer is in the / Applications directory.

How to boot a Mac with MacOS Big Sur USB Install Drive

Booting a Mac with a boot disk is pretty straight forward in most cases ***:

  1. Connect macOS Big Sur beta installer to your Mac
  2. Restart your Mac if it has already started, otherwise you can restart it as usual
  3. Instantly hold down the OPTION key at Mac startup, and hold down OPTION / ALT until you see the Mac startup menu
  4. Select the macOS Big Sur installation volume from which you want to boot your Mac

What if your Mac will not boot from the MacOS Big Sur USB bootable installation drive?

*** Note that on some newer Macs with the security chip, you may need to enable the ability to boot your Mac from an external boot disk. Do this by:

  1. Restart the computer by holding down Command + R to enter recovery mode
  2. Select “Startup Security Utility” from the Tools menu and authenticate with admin
  3. Select to “Allow startup from external media”

This will allow the Mac to boot from the Big Sur boot installation disk as usual with the instructions above.

Anyway, once your Mac has booted from MacOS Big Sur beta installer, you can format Mac OS, partition it, change and create APFS volumes, recover from Time Machine, clean install, upgrade Mac to MacOS Big Sur and much more.

Have you successfully created a bootable installation station of macOS Big Sur with the command line transport described here? Did you use another method to create a Big Sur boot disk? Share your thoughts and experiences in the comments below.

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