Trying to start a Mac from a boot disk but it’s not working? And you’re sure you created the boot drive properly? There may be a few different reasons for this.
Some of the later model Intel Macs have a security chip that offers the prevention of external boot media to be used to startup a Mac. If this setting is enabled on a Mac, the computer will not boot when a USB boot disk or other boot media is used.
Additionally, booting an M1 Mac from external boot disks is different from Intel Macs.
If you’re finding the ability to boot a Mac from an external boot…