Posted   by 

Apple Createinstallmedia



Apple has a new version of macOS. It’s called Big Sur, and it’s version 11.0.In this article I’ll go over how you can create a bootable macOS Big Sur installation drive. Apple has a couple of other commands that you could try. Cut and paste the correct createinstallmedia text into Terminal (the code will depend on the version of macOS. Apple has made the process seamless. It might seem a bit hard at first, but if you follow the steps correctly, you won’t encounter any problem. The major issue with my computer was that I was using an external WiFi adapter. So, I had to first create a bootable drive and then erase the Mac.

  1. Apple Utility Createinstallmedia Download
  2. Apple Createinstallmedia Yosemite
  • Supported version: 0.6.7

While you don't need a fresh install of macOS to use OpenCore, some users prefer having a fresh slate with their boot manager upgrades.

To start we'll want to grab ourselves a copy of macOS. You can skip this and head to formatting the USB if you're just making a bootable OpenCore stick and not an installer. For everyone else, you can either download macOS from the App Store or with Munki's script.

# Downloading macOS: Modern OS

  • This method allows you to download macOS 10.13 and newer, for 10.12 and older see Downloading macOS: Legacy OS

From a macOS machine that meets the requirements of the OS version you want to install, go directly to the App Store and download the desired OS release and continue to Setting up the installer.

For machines that need a specific OS release or can't download from the App Store, you can use the Munki's InstallInstallMacOS utility.

In order to run it, just copy and paste the below command in a terminal window:

As you can see, we get a nice list of macOS installers. If you need a particular versions of macOS, you can select it by typing the number next to it. For this example we'll choose 10:

  • macOS 11, Big Sur Note: As this OS is quite new, there's still some issues with certain systems to resolve. For more information, see here: OpenCore and macOS 11: Big Sur
    • For first time users, we recommend macOS 10.15, Catalina
  • Nvidia GPU Note: Reminder to verify whether your hardware support newer OSes, see Hardware Limitations

This is going to take a while as we're downloading the entire 8GB+ macOS installer, so it's highly recommended to read the rest of the guide while you wait.

Once finished, you'll find in your ~/macOS-Installer/ folder a DMG containing the macOS Installer, called Install_macOS_11.1-20C69.dmg for example. Mount it and you'll find the installer application.

  • Note: We recommend to move the Install macOS.app into the /Applications folder, as we'll be executing commands from there.
  • Note 2: Running Cmd+Shift+G in Finder will allow you to easily jump to ~/macOS-installer
Apple Createinstallmedia

From here, jump to Setting up the installer to finish your work.

# Downloading macOS: Legacy OS

  • This method allows you to download much older versions of OS X, currently supporting all Intel versions of OS X(10.4 to current)

    • Legacy macOS: Offline method
      • 10.10-10.12 Supported
    • Legacy macOS: Online method(10.7-10.15 Supported)
      • 10.7-11 Supported
    • Legacy macOS: Disk Images
      • 10.4-10.6 Supported

# Setting up the installer

Now we'll be formatting the USB to prep for both the macOS installer and OpenCore. We'll want to use macOS Extended (HFS+) with a GUID partition map. This will create two partitions: the main MyVolume and a second called EFI which is used as a boot partition where your firmware will check for boot files.

  • Note: By default, Disk Utility only shows partitions – press Cmd/Win+2 to show all devices (alternatively you can press the View button)
  • Note 2: Users following 'Legacy macOS: Online method' section can skip to Setting up OpenCore's EFI environment

Next run the createinstallmedia command provided by Apple(opens new window). Note that the command is made for USB's formatted with the name MyVolume:

This will take some time so you may want to grab a coffee or continue reading the guide (to be fair you really shouldn't be following this guide step by step without reading the whole thing first).

You can also replace the createinstallmedia path with that of where your installer's located (same idea with the drive name).

Legacy createinstallmedia Commands

Pulled from Apple's own site: How to create a bootable installer for macOS(opens new window)

# Legacy Setup

For systems not supporting UEFI boot, see below:

Setting up Legacy Boot

To start, you need the following:

  • BootInstall_IA32.tool or BootInstall_X64.tool
    • This can be found in OpenCorePkg under /Utilties/LegacyBoot/
  • Install USB(Created above)

Within your OpenCore build folder, navigate to Utilities/LegacyBoot. Here you'll find a file called BootInstall_ARCH.tool. What this does is install DuetPkg to your desired drive.

Now run this tool in terminal with sudo(This tool will likely fail otherwise):

This will give you a list of available disks, choose yours and you will be prompted to write a new MBR. Choose yes[y] and you'll be finished.

This will provide you with an EFI partition with either a bootia32 or bootx64 file

# Setting up OpenCore's EFI environment

Setting up OpenCore's EFI environment is simple – all you need to do is mount our EFI system partition. This is automatically made when we format with GUID but is unmounted by default, this is where our friend MountEFI(opens new window) comes in:

You'll notice that once we open the EFI partition, it's empty. This is where the fun begins.

# Now with all of this done, head to Setting up the EFI to finish up your work

These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.

What you need to create a bootable installer

  • A USB flash drive or other secondary volume formatted as Mac OS Extended, with at least 14GB of available storage
  • A downloaded installer for macOS Big Sur, Catalina, Mojave, High Sierra, or El Capitan

Download macOS

  • Download: macOS Big Sur, macOS Catalina, macOS Mojave, or macOS High Sierra
    These download to your Applications folder as an app named Install macOS [version name]. If the installer opens after downloading, quit it without continuing installation. To get the correct installer, download from a Mac that is using macOS Sierra 10.12.5 or later, or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.
  • Download: OS X El Capitan
    This downloads as a disk image named InstallMacOSX.dmg. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

Use the 'createinstallmedia' command in Terminal

  1. Connect the USB flash drive or other volume that you're using for the bootable installer.
  2. Open Terminal, which is in the Utilities folder of your Applications folder.
  3. Type or paste one of the following commands in Terminal. These assume that the installer is 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 in these commands with the name of your volume.

Big Sur:*

Catalina:*

Mojave:*

High Sierra:*

El Capitan:

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument and installer path, similar to the way this is done in the command for El Capitan.


After typing the command:

  1. Press Return to enter the command.
  2. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
  3. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
  4. After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume. Click OK to allow the copy to proceed.
  5. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Big Sur. You can now quit Terminal and eject the volume.

Use the bootable installer

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes and a gear icon labled Options.
  3. Select the volume containing the bootable installer, then click Continue.
  4. When the macOS installer opens, follow the onscreen instructions.

Intel processor

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
  3. Release the Option key when you see a dark screen showing your bootable volumes.
  4. Select the volume containing the bootable installer. Then click the up arrow or press Return.
    If you can't start up from the bootable installer, make sure that the External Boot setting in Startup Security Utility is set to allow booting from external media.
  5. Choose your language, if prompted.
  6. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

For more information about the createinstallmedia command and the arguments that you can use with it, make sure that the macOS installer is in your Applications folder, then enter the appropriate path in Terminal:

Apple Utility Createinstallmedia Download

  • Big Sur: /Applications/Install macOS Big Sur.app/Contents/Resources/createinstallmedia
  • Catalina: /Applications/Install macOS Catalina.app/Contents/Resources/createinstallmedia
  • Mojave: /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia
  • High Sierra: /Applications/Install macOS High Sierra.app/Contents/Resources/createinstallmedia
  • El Capitan: /Applications/Install OS X El Capitan.app/Contents/Resources/createinstallmedia

Apple Createinstallmedia Yosemite

A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.