Top 5 Reasons macOS Installer USB Doesn’t Show Up at Startup

You’ve created a bootable USB for macOS installation, but when you restart your Mac and hold Option (⌥), the installer doesn’t appear. Frustrating, right? Don’t worry — this guide breaks down the most common reasons your installer USB is missing and exactly how to fix it.

🔍 Reason 1: USB Not Properly Formatted

The most common issue is an improperly formatted USB drive. macOS requires:

• Format: Mac OS Extended (Journaled)
• Scheme: GUID Partition Map

To fix:

1. Open Disk Utility
2. Select the USB drive, click Erase
3. Choose the correct format and scheme
4. Recreate the installer

⚠️ Reason 2: macOS Installer Creation Failed

If the createinstallmedia command failed during creation, your USB won’t boot. Always confirm Terminal reports success. If unsure:

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

Re-run the command and check for errors. Learn more in our guide on how to create macOS bootable USB.

🔒 Reason 3: Secure Boot Settings

On T2 and Apple Silicon Macs, Secure Boot may block bootable external drives. You need to adjust settings in Recovery Mode:

1. Restart your Mac in Recovery (Command + R or press and hold Power)
2. Go to Startup Security Utility
3. Select Allow booting from external media

💡 Reason 4: USB Port or Adapter Issue

Sometimes it’s as simple as the port. Try:

• Switching USB ports (especially from USB-C hubs)
• Using a different adapter if needed
• Testing the USB on another Mac to see if it appears there

🧩 Reason 5: Installer Version Not Compatible

If you’re trying to install an older version of macOS on a newer Mac, it may simply not show up at startup. Learn more about installer compatibility errors. Check Apple’s support site for the macOS compatibility list and ensure your installer matches your Mac’s supported versions.

🔧 Bonus Fix: Use Startup Disk Preferences

If your USB shows up on the desktop but not at boot, try selecting it manually:

1. Go to System Preferences → Startup Disk
2. Select the installer USB and restart

🧠 Final Thoughts

macOS installer USBs can be finicky, but once you address these common issues — formatting, creation errors, Secure Boot, or compatibility — you’ll be back in business. Always double-check your tools, and don’t hesitate to try on a second Mac for testing.

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• How to Fix a Frozen Computer

❓ Frequently Asked Questions

Why is my macOS USB not showing up when I hold Option?

It’s often due to formatting issues, a failed installer creation, or Secure Boot restrictions.

Does the USB need to be formatted as APFS?

No. macOS installers require Mac OS Extended (Journaled) with GUID Partition Map.

Can I use a USB-C flash drive?

Yes, but verify that it’s readable by your Mac and compatible with your adapter or port.

Can Secure Boot block my USB installer?

Yes. You need to allow booting from external media in the Startup Security Utility.

What if my USB shows up on another Mac but not mine?

This usually points to Secure Boot or firmware compatibility issues. Try another USB or adjust your startup security settings.