Some years ago it was easy to clone the current system partition of a Mac computer to an external firewire hard disk and then use this as a startup disk for the same Mac or even for another Mac.

When I currently tried this with a USB drive (Western Digital Expansion+) and cloned the SSD of my MacBook to it and tried to boot another MacBook (different model) with it (by holding option key while booting), it was not recognized as a possible startup disk.

What could be the reason for it? Are USB drives more difficult than Firewire as startup disks? Or is it more difficult today to use the same system configuration on a different MacBook model?

The source was the SSD of a MacBook mid 2012. I'm not sure and currently can not find out, how old the other MacBook was...

  • 2
    What model is your Mac? The latest models have external booting disabled by default. support.apple.com/en-gb/HT208198
    – benwiggy
    Feb 22 '20 at 11:31
  • @benwiggy: good question - I've edited my question, but I do not know and can't find it out at the moment. However, in the linked support article, there is an error message shown about "security settings" in the startup disk control panel, and I did not see this (I also tried to select the drive in the system settings) Feb 22 '20 at 11:40
  • 1
    There are limitations on which version of macOS / OS X can boot which hardware. If the source OS was also from 2012, it could be as old as OS X 10.7, aka Lion, which would not run on modern Macs.
    – da4
    Feb 22 '20 at 13:21
  • @da4: the cloned OS was OS X 10.11 Feb 25 '20 at 16:38

Recently I ran into a similar problem. See Problem cloning the startup disk of a MacBook Pro running OS X 10.11.6 El Capitan .

Keep an eye on how you cloned your system partition residing on the SSD. I guess your system partition is of type CoreStorage. If so, the recipe I figured out for cloning the startup disk may be useful to you.

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