Downgrading from 10.13 back to 10.12

Discussion in 'macOS High Sierra (10.13)' started by greg624, Jul 11, 2017.

  1. greg624 macrumors regular


    Jul 31, 2013
    So I finally got tired of High Sierra, but I want to clean install Sierra back onto my 2017 MacBook Pro. Problem is, I created a Sierra boot drive but trying to boot into it makes it go to a prohibitory sign. The USB boot drive works fine on my old 2011 MacBook Pro... but doesn't on this laptop for some reason. Is there any way to fix that? Command + R just goes into the High Sierra Recovery and it will just clean install 10.13...
  2. Spazturtle macrumors member

    Sep 17, 2013
  3. greg624 thread starter macrumors regular


    Jul 31, 2013
    I’m one of those that unfortunately don’t have a Time Machine back up.

    I know the risks of running beta software as well, when I bought the computer I had put High Sierra on it instantly but unfortunately Beta 3 made everything worse. So I’m trying to figure out some way to downgrade. Some people have found a way on this forum but haven’t posted a solution, even after finding this solution days ago.
  4. chrfr macrumors 604

    Jul 11, 2009
    You’ll need to use command-option-shift-R to use internet recovery to get back to whatever version of OS X shipped with your computer. Then, once in recovery, open Disk Utility and format your disk. You will lose everything on the disk when you do this, so copy any files you want to another disk before you do anything with reverting your disk.
  5. Fishrrman macrumors Pentium


    Feb 20, 2009
    OP wrote:
    "I’m one of those that unfortunately don’t have a Time Machine back up."

    Lesseeee here....
    No backups?
    And you tried new, totally beta software that was unproven on your main machine?
    And now, you want to go back?

    Ahem.... isn't that what "backups" are for?

    I suggest you download CarbonCopyCloner from here:
    CCC is FREE to download, and it's FREE to use for 30 days.

    Next, connect an external drive to the Mac.
    Use CCC to create a clone of the internal drive on the external drive. Easy enough.

    NOW, try the internet recovery process outlined by chrfr above.

    I suggest that you run Disk Utility first, and completely re-initialize the internal drive.
    Then, do a clean install onto it.

    After the install is done, before you reboot "into it", connect the CCC cloned backup.

    Now reboot and go through the initial setup sequence.

    At the appropriate moment, the Setup Assistant will ask if you want to migrate data from another computer or drive.

    "Aim it" at the cloned backup.
    Choose to migrate apps, accounts.
    I might leave "settings" UNchecked, because preference files created in High Sierra might not work in [regular] Sierra.
    Bring over data, too.

    That oughta do it.

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