Creating a Bootable USB for macOS: A Detailed Guide

Introduction

A bootable USB drive for macOS is an essential tool for installing or recovering the operating system. It allows you to:

• Install macOS on a new or formatted disk.
• Recover the system in case of serious failures.
• Perform a clean installation without booting into the current system.

By following this guide, you will create a bootable USB drive in 15–20 minutes using only macOS's built-in tools.

Requirements and Preparation

Before you begin, make sure you have:

1. USB drive with at least 16 GB of storage (32 GB or more is recommended). All data on it will be erased.
2. Mac computer running macOS Ventura 13.0 or newer.
3. macOS installer image for the desired version. You can download it from the App Store (e.g., "macOS Ventura" or "macOS Sonoma"). The image will take up about 12–16 GB.
4. Stable internet connection to download the image (if you don't already have it).
5. Administrator privileges on your Mac (you will need a password for sudo commands).

⚠️ Important: Do not use a USB drive that contains important data—everything will be erased during the formatting process.

Step-by-Step Instructions

Step 1: Prepare the USB Drive

1. Connect the USB drive to your Mac.
2. Open Disk Utility (via Spotlight or Applications → Utilities).
3. In the left sidebar, select the USB drive itself (the physical disk, not a partition).
4. Click Erase.
5. Set the parameters:
   • Name: MyUSB (or any other name without spaces or Cyrillic characters, e.g., InstallUSB).
   • Format: Mac OS Extended (Journaled) or APFS (APFS is recommended for macOS Catalina and newer).
   • Scheme: GUID Partition Map.
6. Click Erase. Wait for the process to complete.

Step 2: Download the macOS Installer Image

1. Open the App Store.
2. In the search field, enter the name of the macOS version (e.g., "Ventura" or "Sonoma").
3. Find the "macOS Version" page and click Download.
4. The installer app will begin downloading to the /Applications folder. The size is approximately 12–16 GB; download time depends on your internet speed.
5. After downloading, you will see a file named Install macOS [Version].app in /Applications.

💡 Tip: If you have already downloaded the image previously, it might be in the /Applications folder. Ensure it is the correct version.

Step 3: Identify the USB Drive's Identifier

1. Open Terminal (via Spotlight or Applications → Utilities).
2. Enter the command:

   diskutil list
   

3. In the output, find your USB drive by its size (e.g., 16 GB) and name (e.g., MyUSB). It will typically have an identifier like disk2, disk3, etc. Example output:

   /dev/disk2 (internal, physical):
      #:                       TYPE NAME                    SIZE       IDENTIFIER
      0:      GUID_partition_scheme                        *16.0 GB   disk2
      1:                        EFI EFI                     209.7 MB   disk2s1
      2:                 Apple_HFS MyUSB                    15.7 GB   disk2s2
   

   Here, the disk identifier is disk2 (note disk2, not disk2s2).

Step 4: Create the Bootable Media

1. In Terminal, run the command, replacing [Version] with your macOS version (e.g., Ventura) and MyUSB with your volume's name:

   sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/MyUSB
   

   • If your volume name contains spaces, use a backslash \ to escape them (as shown above) or enclose the path in quotes.
   • If you have Sonoma installed, the command will be:

     sudo /Applications/Install\ macOS\ Sonoma.app/Contents/Resources/createinstallmedia --volume /Volumes/MyUSB
     

2. Enter your administrator password (characters will not be displayed—this is normal).
3. Confirm the disk erase by typing Y (yes).
4. The process will take 10–20 minutes. You will see progress as a percentage. Do not interrupt it.

⚠️ Important: Ensure the path to createinstallmedia specifies the correct macOS version. If you have multiple installer apps, check the folder name in /Applications.

Step 5: Verify Completion

After successful completion, Terminal will display:

Install media now available at "/Volumes/MyUSB"

Your USB drive will be renamed to Install macOS [Version].

Verify the Result

1. Restart your Mac.
2. Immediately after powering on, hold the Option (Alt) key.
3. In the bootable disk selection menu, your USB drive should appear with the label Install macOS [Version].
4. Select it to boot into the macOS installer and perform an installation or recovery.

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Troubleshooting Common Issues

Error: "No such file or directory"

• Cause: Incorrect path to the installer image.
• Solution: Check the folder name in /Applications using ls /Applications. Ensure the command uses the exact name (e.g., Install macOS Ventura.app).

Error: "diskutil unmountDisk failed"

• Cause: The disk is already mounted or in use by the system.
• Solution: Manually unmount the disk:

  diskutil unmountDisk /dev/diskX
  

  Replace diskX with your identifier (e.g., disk2). Then retry the creation command.

Error: "The volume could not be unmounted"

• Cause: The USB drive is being used by another process.
• Solution: Close all applications that might access the disk (e.g., Finder, Time Machine). Try ejecting and reinserting the USB drive.

Not Enough Space on the USB Drive

• Cause: The macOS image requires more space than available.
• Solution: Use a USB drive with a larger capacity (minimum 16 GB, but 32 GB is recommended).

USB Drive Does Not Appear in the Boot Menu

• Cause: Incorrect formatting or a corrupted image.
• Solution:
  1. Reformat the USB drive using Disk Utility (as in Step 1).
  2. Ensure you used the format Mac OS Extended (Journaled) or APFS.
  3. Repeat the bootable media creation process.

createinstallmedia Command Not Found

• Cause: The installer image was not downloaded or has a different name.
• Solution: Check for the file:

  ls /Applications/Install\ macOS*/Contents/Resources/createinstallmedia
  

  If the file is missing, redownload the installer image from the App Store.