MacBook Pro 2018: Downgrade Mojave back to High Sierra

Discussion in 'macOS Mojave (10.14)' started by GonzMac, Jul 20, 2018.

  1. GonzMac macrumors newbie

    GonzMac

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    #1
    I'm trying to downgrade from Mojave back to High Sierra, which is now seemingly impossible. I used my iMac to download High Sierra from the Mac App Store and created a bootable external hard drive to try and reinstall High Sierra. I tried booting from the external HD to begin the install and I get a circle with a cross in it (almost like a stop sign). I've tried the recovery tool and the MacBook Pro ends up just looping thru the recovery process but never installs High Sierra. The only thing I can manage to do is reinstall Mojave. Would it be possible for me to create a time machine backup of my iMac (which is running High Sierra) and launch the recovery tool on my MacBook Pro and restore from the time machine backup? Any suggestions?
     
  2. David58117 macrumors 65816

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    #2
    It was a nightmare when I did it (with a single MacBook Pro).

    It would only let me reinstall Mojave, and internet recovery kept giving me an error. I think I had to reinstall Mojave (after I formatted the drive), then download (and run) High Sierra from the App Store. I don't remember if I had to unenroll it from the Beta Profile too, but I remember High Sierra not appearing on the App Store initially.

    All together it was pretty aggravating for awhile.
     
  3. GonzMac thread starter macrumors newbie

    GonzMac

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    #3
    Do you have a 2018 MacBook Pro? I’m wondering if that’s the reason I’m struggling so much.
     
  4. David58117 macrumors 65816

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    #4
    It was a 2016.

    It seemed like Mojave replaced HS at the recovery partition, and like the beta profile (at least for me, on one computer) wouldn't let me download HS from the App Store.

    But *I think* (since it's been a few weeks), that once I had the HS installation downloaded on the machine and started the process by running the installation, it was finally able to install (also I think I had to remove it from the beta profile).
     
  5. GonzMac thread starter macrumors newbie

    GonzMac

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    #5
    I'll give that a shot. Thank you!
     
  6. DeltaMac macrumors G3

    DeltaMac

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    #6
    Yes, your 2018 came with a build of High Sierra that is newer than the 10.13.6 that you would normally download (and which will not boot on your new MBPro). You can follow the steps in this thread to get that 2018 MBPro build.
    Go to post #14 in that thread, then follow the links to get the python script, etc. The 10.3.6 build 17G2112 is the one that you want.
     
  7. GonzMac thread starter macrumors newbie

    GonzMac

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    #7
    Thank you! I will definitely give this a go when I get out of work. I had assumed it had something to do with the MBP running a newer version of High Sierra but you'd think Apple would of updated their own internet recovery tool to support their latest MBPs.
     
  8. bendrumin macrumors 6502

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    #8
    It can also be done by using internet recovery, downloads the exact high sierra build for the laptop
     
  9. ckeck macrumors 6502a

    ckeck

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    #9
    This does not seem to be the case. Just as OP mentioned, the internet recovery option just keeps looping through the install process over and over.

    I'm experiencing the exact same issue trying to go back to High Sierra.
     
  10. GonzMac thread starter macrumors newbie

    GonzMac

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    #10
    I still haven't been able to downgrade. I've tried every possible thing and the laptop ends up looping in both internet recovery and external usb with macOS High Sierra (I was even able to get the exact version the laptop shipped with) recovery, it always ends up looping over and over again. The only OS I have been able to install without a problem is an external usb with Mojave beta. The install goes smoothly.
     
  11. DeanLubaki, Jul 21, 2018
    Last edited: Jul 21, 2018

    DeanLubaki macrumors 6502

    DeanLubaki

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    #11
    There are three ways to Recovery HD:

    1. Command (⌘)-R: Install the latest macOS that was installed on your Mac, without upgrading to a later version.
      By doing this, you will only be able to reinstall Mojave.

    2. Option-Command-R: Upgrade to the latest macOS that is compatible with your Mac.
      By doing this, it will launch internet recovery to find the latest macOS compatible with your Mac.

    3. Shift-Option-Command-R: Install the macOS that came with your Mac, or the version closest to it that is still available.
      By doing this, it will launch internet recovery to find the version of macOS that came with your Mac.

    You should try method 2 and 3.
     
  12. Fishrrman macrumors P6

    Fishrrman

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    #12
    RE Dean's post 11 above:

    That's a very concise and useful listing, Dean.
    EVERY Mac owner who reads this should copy Dean's post, and save this info someplace!

    I did.
     
  13. GonzMac thread starter macrumors newbie

    GonzMac

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    #13
    Read my post (#10), I've tried all these methods. Just going to have to wait until the next beta to fix all the incompatibilities with the 2018 MBPs.
     
  14. DeanLubaki, Jul 22, 2018
    Last edited: Jul 22, 2018

    DeanLubaki macrumors 6502

    DeanLubaki

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    #14
    Your post #10 did not specify which internet recovery you did. As you can see on my post, there are two ways to do internet recovery that do not necessarily install the same version of macOS.
     
  15. GonzMac thread starter macrumors newbie

    GonzMac

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    #15
    I tried both methods (#2 and #3) both result in the same issue: a looping install of macOS High Sierra. Which never installs and forces me to restart the computer, erase the hard drive, and reinstall macOS Mojave beta.
     
  16. Fishrrman macrumors P6

    Fishrrman

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    #16
    OP:

    I think the reason for your problems is the fact that you have a just-released 2018 MacBook Pro.

    Apple hasn't got the proper means available yet to "downgrade".
    I'm wondering if this has something to do with the "t2" chip inside.

    A thought:
    Is there any way to completely DISABLE the t2 chip?
    If there is, I'd try that (temporarily) and try again.
     
  17. GonzMac thread starter macrumors newbie

    GonzMac

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    #17
    That's what I had assumed. Thats why I even tried getting the same exact version of High Sierra the MBP 2018 shipped with and the install would not stop looping. It would act like its installing, the computer restarts, and the whole installation cycle starts again. I did temporarily disable the T2 booting controller while in recovery to allow external HD. Still made no difference.
     
  18. Sovon Halder macrumors 6502

    Sovon Halder

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    #18
    What r the problems u r facing ??
     
  19. DeanLubaki macrumors 6502

    DeanLubaki

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    #19
    Best thing to do at this point is return to the store to swap it.
    That's what I did for mine when it bricked
     
  20. anticipate macrumors 6502

    anticipate

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    #20
    There is no internet recovery on T2-equipped Macs (iMac Pro, 2018 MBP). You have to use another Mac with configurator installed to restore the machine if the recovery partition is messed up. I know, huge pain in the ass. I always loved Internet Recovery.
     
  21. GonzMac thread starter macrumors newbie

    GonzMac

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    #21
    Do you know where I can get the configurator tool?
     
  22. Fishrrman macrumors P6

    Fishrrman

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    #22
    anticipate wrote:
    "There is no internet recovery on T2-equipped Macs (iMac Pro, 2018 MBP). You have to use another Mac with configurator installed to restore the machine if the recovery partition is messed up. I know, huge pain in the ass. I always loved Internet Recovery."

    Geesh -- one more big step backwards.
    No internet recovery.
    No way to recover contents of the internal drive before a motherboard swap.
    Need A SECOND MAC for a reinstall/recovery if the recovery partition fails.

    Folks... is this progress?
    Especially considering the escalating price tags of new MacBooks?

    I've said it before, and I'll say it again:
    Am I glad I looked at the "new design" MBP's in December 2016... and then decided to buy the 2015 design instead !!!!
     
  23. Sovon Halder macrumors 6502

    Sovon Halder

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    #23
    Yeah.

    So you looked at... bigger trackpad, super high bandwidth next gen ports, better display, better sound, better graphics, way faster ssd, faster cpu, hardware hevc which would be standard for next decade, an overall better industrial build - all of that. And decided to go with an older product.

    And you justify your decision by making a point that it has an OS re-install method (internet recovery)? Don't know mate. If you got a good deal with price good for you, otherwise meh!
     
  24. steveaburns macrumors member

    steveaburns

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    Palo Alto, CA
    #24
    It could be a long shot, but I'm wondering whether installing the MBP 2018 HS version on another mac, and using a cloner like CCC or SuperDuper to erase and duplicate onto your MBP 2018 could work?? Don't have the cables to attach your MBP 2018 in target disk mode, the you could also duplicate to an External drive, then plug it into your MBP 2018 and boot from it, and duplicate onto the MBP...
     
  25. Fishrrman macrumors P6

    Fishrrman

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    #25
    "So you looked at... bigger trackpad, super high bandwidth next gen ports, better display, better sound, better graphics, way faster ssd, faster cpu, hardware hevc which would be standard for next decade, an overall better industrial build - all of that. And decided to go with an older product."

    Yup.

    I wanted a keyboard that "felt right" to me and legacy ports that would work with the stuff I had. I didn't like the too-large trackpad from the first moment I used it -- preferred the standard-size one of the 2015 design. Didn't like the 2016 keyboard AT ALL.

    Going on two years later...
    - My keyboard has been flawless.
    - The display looks fine to me.
    - The SSD is as fast as I can use, as is the CPU (does everything I do "fast enough").
    - I still don't own a USB-c device.

    In hindsight, choosing the 2015 MacBook Pro over the 2016 was the best computer-buying decision I've ever made... ;)
     

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