I'm trying to make an external SSD that can boot my MacBook, using Big Sur. I formatted the SSD as APFS. I downloaded the app Install macOS Big Sur. The app installed Big Sur on the external SSD. I then change the Startup Disk to the external SSD. When I click "Restart" I get this error:
I tried all this twice and got the same error message. What's wrong?
MacBook Pro 15″, macOS 11.6
are you trying to create a bootable installer? if yes, please see this article: How to create a bootable installer for macOS – Apple Support
or are you trying to set up an independent start up drive? if yes, please see this informative, well written user tip: How to Setup and Use an External SSD as your Startup Disk - User Tip
are you trying to create a bootable installer? if yes, please see this article: How to create a bootable installer for macOS – Apple Support
or are you trying to set up an independent start up drive? if yes, please see this informative, well written user tip: How to Setup and Use an External SSD as your Startup Disk - User Tip
Hello Thomas Kehoe,
Looking over the Apple Support article How to create a bootable installer for macOS - Apple Support, I believe you have the SSD formatted incorrectly.
“What you need to create a bootable installer
I hope this helps.
Search Apple Support of Secure Enclave or Secure Boot . Applies only to Apple computers with the T2 Chip
How do I make a bootable startup external SSD? SDErrorDomain error 104.
