Fix IA App name cookie write failed when creating Bootable USB in macOS?

When trying to create a macOS bootable USB, you might encounter the dreaded error message: “IA App name cookie write failed”. This can sometimes be accompanied by “The Copy of the installer app failed” or “The bless of the installer disk failed”. These errors often stem from permission issues, installer problems, or improperly formatted drives.

In this guide, we’ll walk you through how to fix these issues using Terminal permissions, USB preparation, and more. Let’s get started.

Enable Full Disk Access for Terminal

If you’re using Terminal to run the createinstallmedia command, Terminal must have Full Disk Access.

Steps to Grant Full Disk Access:

1. Click on the Apple logo in the top-left corner and go to System Settings.
2. Navigate to Privacy & Security → Full Disk Access.
3. Enable access for Terminal.
   
   

If Terminal is Missing:

1. Click the + button.
2. Navigate to Applications > Utilities.
3. Select Terminal and click Open.
4. Re-lock settings and restart Terminal for changes to take effect.

Fixing Common Bootable USB Errors

1. “IA App name cookie write failed”

• Verify that you have write permissions to the USB and Applications folder.
• Try using a different USB port.
• Ensure Terminal has Full Disk Access (see above).

2. “The Copy of the Installer App Failed”

• Ensure your USB has at least 16GB of space.
• Check your Mac’s disk health using Disk Utility’s First Aid feature.
• Re-download the macOS installer from the IA App Name error fix guide or Apple Support.

3. “The Bless of the Installer Disk Failed”

• Make sure your USB is formatted as Mac OS Extended (Journaled) with GUID Partition Map.
• Reset NVRAM using these NVRAM reset and bless error fix steps.

How to Properly Prepare Your USB Drive

• Use Disk Utility to erase the USB drive and choose:
  • Format: Mac OS Extended (Journaled)
  • Scheme: GUID Partition Map
• Make sure you use a reliable USB brand for better success rates.

Use the Correct Terminal Command

Run the correct createinstallmedia command using sudo. For example:

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

Important Notes:

• Replace Ventura with the correct macOS version.
• Do not interrupt the process once it begins—it may take a while.

Still Stuck? Try These

• Update your macOS to the latest version available.
• Temporarily disable antivirus or firewall software.
• Review logs in the Console app for more detailed error info.

For step-by-step USB creation, follow our detailed guide here:
How to Create macOS Bootable USB