How to Boot T2 Mac from External Startup Drive

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Apple has equipped newer Macs with security features that do many things to help your computer be more secure — the Touch ID, Touch Bar, and/or the T2 security chip. By default, Macs equipped with the T2 processor will not boot from any external drive. It is actually good because it only allows your Mac from secure devices.

With T2 chips in place, Apple advises users to use Internet Recovery to reinstall macOS when an incident happens. But we all know that not everyone has a great internet connection. There are also instances when Internet Recovery encounters an error and fails to install macOS.

In cases like these, booting from a bootable external drive is the only option. But if your Mac has a T2 chip, you might have a huge problem since it does not allow booting from external sources. This makes the troubleshooting process a lot longer and more complicated.

Imagine this scenario: your Mac suddenly won’t boot due to a hard drive problem and you need to access your Time Machine close saved on an external drive. If your Mac does not have the T2 chip, all you need to do is plug in your backup drive and boot from there. No productivity lost and no stress for you.

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But with T2 chips installed on newer Macs, you can’t simply connect your external drive and boot from it. Your Mac probably won’t even recognize it. While your Mac is still working fine, you need to allow a T2 equipped Mac to boot from external startup drives by tweaking the settings. This way, whatever emergency happens, you don’t have to worry about any restrictions when you’re troubleshooting your computer.

How to Know if Your Mac Has a T2 Processor

It is necessary to check if your Mac has a T2 Chipset because newer machines have designed them to add extra layers of security. You will need to take different or additional steps when troubleshooting something, depending on whether your Mac has a T2 Security Chip or not.

This is the complete list of Macs that are equipped with the T2 processor:

  • iMac Retina 5K, 27-inch, 2020
  • iMac Pro
  • Mac Pro 2019
  • Mac Pro Rack, 2019
  • Mac mini 2018
  • MacBook Air Retina, 13-inch, 2020
  • MacBook Air Retina, 13-inch, 2019
  • MacBook Air Retina, 13-inch, 2018
  • MacBook Pro 13-inch, 2020 with Two Thunderbolt 3 ports
  • MacBook Pro 13-inch, 2020 with Four Thunderbolt 3 ports
  • MacBook Pro 16-inch, 2019
  • MacBook Pro 13-inch, 2019 with Two Thunderbolt 3 ports
  • MacBook Pro 15-inch, 2019
  • MacBook Pro 13-inch, 2019 with Four Thunderbolt 3 ports
  • MacBook Pro 15-inch, 2018
  • MacBook Pro 13-inch, 2018 with Four Thunderbolt 3 ports

If your device is on the list, then it probably has a T2 chip. To be sure, you can also check the Controller information by following the steps below:

  1. Press and hold the Option button while clicking Apple menu > System Information.
  2. In the sidebar, choose either Controller or iBridge, depending on your version of macOS.
  3. If you see Apple T2 chip on the right, then your Mac is equipped with the Apple T2 Security Chip.

If your Mac is offline or won’t boot, you can check whether it has a T2 Security Chip by verifying the device’s serial number or model number found on the underside of your Mac. The serial number is usually composed of a 12-digit alphanumeric code while the model number consists of the letter A followed by a 4-digit code.

Once you have this information, you can go to either of these websites to check whether your device comes with a T2 chip:

How to Allow External Drive Booting on Mac with T2 Chip

If you’re looking to boot from an external drive on a T2-equipped device, consider enabling it from Recovery Mode. Before doing so, you may want to optimize your Mac to minimize other potential issues. One option for this is using a tool like Outbyte macAries. Ensure it suits your needs.

Once you’ve got everything ready, follow the instructions below:

  1. Boot your Mac and immediately hold down the Command + R keys.
  2. When you see the Apple logo on the screen, continue holding the keys until the computer boots into MacOS Recovery Mode.
  3. Authenticate using an admin user account.
  4. At the macOS Utilities screen, pull down the Utilities menu located at the top.
  5. Choose Startup Security Utility from the menu bar options.
  6. Enter your admin password when prompted.
  7. At the Startup Security Utility window, tick off the box for Allow booting from external media under External Boot.
  8. Close the window.

Your Mac should now be able to boot from external drives. You will be taken back to the macOS Recovery window where you will be asked whether you want to restart. Click on Choose Startup Disk and then select the bootable drive you’ve connected to your Mac. Your Mac will then restart and boot from that drive.


T2 chips are great because they add an extra layer of security for your Mac. In this age where cyberattacks are rampant and Mac computers are more vulnerable to malware, having this security feature adds to the security of your device. Unfortunately, it becomes an inconvenience when you’re trying to troubleshoot your Mac and you can’t use Internet Recovery. In this case, you can follow the instructions above to allow a T2 equipped Mac to boot from external startup drives.

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