How to create a Bootable macOS Monterey USB installer?

Creating a bootable official macOS Monterey USB installer on a Mac is a straightforward process using the Install macOS Monterey.app and a USB drive. This method uses built-in macOS tools, specifically the createinstallmedia command, to make a bootable installer that can be used to install Monterey on a compatible Mac or troubleshoot an existing system.

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Prerequisites

• macOS Monterey Installer: The full Install macOS Monterey.app (about 12-13GB), downloaded to /Applications. If you don’t have it, see the note at the end on how to obtain it.
• USB Drive: At least 16GB capacity (32GB recommended for reliability).
• Mac with Admin Access: You’ll need a Mac to run the commands and an admin password.
• Time: About 20-30 minutes, depending on USB speed.

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Below are the detailed steps to create bootable macOS Monterey USB installer:

Step-by-Step Instructions to create bootable macOS Monterey USB installer:

1. Prepare the USB Drive

• Insert the USB Drive:
  • Plug your USB drive into your Mac. It will appear in Finder or on the Desktop.
• Open Disk Utility:
  • Go to Applications > Utilities > Disk Utility, or search via Spotlight (Command + Space, type “Disk Utility”).
• Erase the USB Drive:
  • In Disk Utility, select your USB drive from the left sidebar (choose the top-level device, not a partition, e.g., “16.0 GB SanDisk”).
  • Click Erase in the top toolbar.
  • Set the following:
  • Name: MontereyUSB (or any name you prefer).
  • Format: Mac OS Extended (Journaled) (required for the bootable installer).
  • Scheme: GUID Partition Map.
  • Click Erase. This formats the drive, erasing all data—ensure you’ve backed up anything important.
• Verify Mount Point:
  • After erasing, the USB should mount as /Volumes/MontereyUSB (or your chosen name). Confirm in Finder or Terminal:
    ls /Volumes/

2. Locate the Monterey Installer

• Ensure the Install macOS Monterey.app is in /Applications:
  ls /Applications/ | grep "Install macOS Monterey"
• If it’s not there, move it from wherever you downloaded it (e.g., ~/Downloads):
  mv ~/Downloads/Install\ macOS\ Monterey.app /Applications/
• Check its size to confirm it’s the full installer (should be ~12GB):
  du -sh /Applications/Install\ macOS\ Monterey.app

3. Create the Bootable Installer

• Run the createinstallmedia Command:
  • Open Terminal (Applications > Utilities > Terminal).
  • Enter this command, replacing MontereyUSB with your USB’s volume name if different:
    sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/MontereyUSB --nointeraction
  • Breakdown:
  • sudo: Runs the command with admin privileges.
  • --volume: Specifies the target USB drive.
  • --nointeraction: Automates the process without prompts.
• Enter Admin Password:
  • Type your password when prompted (it won’t show as you type) and press Enter.
• Wait for Completion:
  • The process erases the USB, copies the installer files, and makes it bootable. It takes 10-20 minutes, depending on USB speed.
  • Terminal output will show progress (e.g., “Copying installer files…”), ending with:
    Install media now available at "/Volumes/Install macOS Monterey"

4. Verify the Bootable USB

• After the command finishes, the USB will be renamed to Install macOS Monterey and mounted at /Volumes/Install macOS Monterey.
• Check in Finder—it should appear as a bootable installer with a Monterey icon.
• Confirm its contents:
  ls /Volumes/Install\ macOS\ Monterey/
• You’ll see system files like InstallESD.dmg and boot files.

5. Eject the USB

• Safely eject the USB:
  • In Finder, click the eject icon next to Install macOS Monterey.
  • Or in Terminal:
    diskutil eject /Volumes/Install\ macOS\ Monterey
• Remove the USB drive once ejected.

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Using the Bootable USB

• Install Monterey:
• Insert the USB into the target Mac.
• Power on the Mac while holding Option (⌥) until the boot menu appears.
• Select Install macOS Monterey from the list and follow the on-screen instructions to install.
• Unsupported Macs: If your Mac isn’t officially supported (e.g., pre-2014 models), you’ll need a tool like OpenCore Legacy Patcher (OCLP) to bypass compatibility checks—apply the patch after creating the USB.

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Troubleshooting

• “Command not found” or “Permission denied”:
• Ensure the installer path is correct (/Applications/Install\ macOS\ Monterey.app). If it’s a beta version, the name might differ (e.g., Install macOS Monterey Beta.app—adjust the command).
• Use sudo and verify your password.
• “Volume not found”:
• Check the USB’s mount point with ls /Volumes/. Adjust the command if the name differs (e.g., /Volumes/MyUSB).
• Slow Process:
• Use a USB 3.0 drive and port for faster copying if available.

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How to Get the Monterey Installer (If Missing)

If you don’t have Install macOS Monterey.app:

• Mac App Store (Supported Macs):
• On a compatible Mac (e.g., 2014 MacBook Pro or later), open the App Store, search for “Monterey,” and download it. It lands in /Applications.
• gibMacOS (Unsupported Macs):
• Clone the gibMacOS repo:
  git clone https://github.com/corpnewt/gibMacOS.git cd gibMacOS python3 gibMacOS.command
• Select Monterey (macOS 12.x), download the .pkg, and extract it to /Applications/Install macOS Monterey.app (see earlier details if needed).

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Notes

• Space: The USB needs to be empty and formatted correctly—16GB minimum ensures no size issues.
• Time: Formatting takes seconds; copying the installer takes longer (e.g., 15 minutes on USB 2.0, faster on USB 3.0).
• Reusability: You can reuse this USB for multiple installs or erase it later with Disk Utility.

You now have a bootable macOS Monterey USB installer.