Trying to reinstall OS but getting errors

Discussion in 'iMac' started by davesmith123, Nov 7, 2018.

  1. davesmith123 macrumors newbie

    Joined:
    Sep 13, 2018
    #1
    I have managed to erase the disk but when I tried to reinstall the OS, I got an error "Could not create a preboot volume for APFS". Based on what I read online, I unmounted the disk and and then tried to erase it and reformat it into Mac OS Extended (Journaled). Then I keep getting an error "Erase process has failed" I've got not idea where to go from here!!

    Please help. Thanks :)

    See screenshots of what I'm currently able to see/do attached. Please ask any questions that'll help you understand better.

    It's a late 2009 iMac.

    2be97509-eb39-482d-8edc-e6ca08143055.jpg 25f63fdd-8f63-4076-a95c-bb18c2ca94cf.jpg 0847e340-2be2-4c97-9ab0-463d6b1d870d.jpg caf93efa-3530-42c0-99ef-a1f6463cd1e0.jpg 99873b18-1c82-4bdf-bc27-22ff6a8c0b03.jpg aeda5ca5-ca99-4edb-8ab8-70405922871d.jpg
     
  2. chrfr macrumors 604

    Joined:
    Jul 11, 2009
    #2
    In Disk Utility, click on the container, and then click Unmount. You should then be able to erase the entire disk as HFS Extended (Journaled).
     
  3. davesmith123 thread starter macrumors newbie

    Joined:
    Sep 13, 2018
    #3
    I don't see an unmount button. I've clicked everything else (even mount, which does nothing).

    This is the error I get when I try to format the container 1 disk to Mac OS Extended 49b2e3c2-3e4a-4a28-881f-fca0caa6be48.jpg
     
  4. chrfr macrumors 604

    Joined:
    Jul 11, 2009
    #4
    Oh, you're trying to erase the entire disk, which is where the Recovery partition is located, so you can't unmount that recovery partition. Since your computer doesn't support internet recovery, you'll need a USB boot drive to erase the entire disk.
     
  5. davesmith123 thread starter macrumors newbie

    Joined:
    Sep 13, 2018
    #5
    How do I do that? Thanks.
     
  6. chrfr macrumors 604

    Joined:
    Jul 11, 2009
    #6
    I edited my post after you replied. Your computer doesn't support internet recovery, sorry about that. You'll need a USB drive, or if you have an older version of macOS on DVD, you can boot from that too.
     
  7. davesmith123 thread starter macrumors newbie

    Joined:
    Sep 13, 2018
    #7
    OK, thanks. Gonna put together a USB boot disk and see what happens. Appreciate you taking the time to respond!
     

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6 November 7, 2018