Please Help! Cannot reinstall Sierra on iMac 2011

Discussion in 'iMac' started by gk32, May 17, 2017.

  1. gk32 macrumors newbie

    May 17, 2017
    Help please! I have iMac 2011, get it last year from craigslist with El Capitan on that moment. Upgraded to Sierra recently. Then decided to erase disk and reinstall. But now I cannot because it shows that disk is locked.

    Here are details.

    1. I restarted iMac

    2. No keys need to be pressed/hold - it goes directly to macOS Utilities with a 4 options: Restore from Time Machine Backup (I don't have backup), Reinstall macOS, Get Help Online, Disk Utility

    3. I select Reinstall macOS, then Continue

    4. Opens window macOS Sierra, where I click Continue

    5. After clicking Agree with license agreement it goes to next window

    6. Here under macOS Sierra I see label "Select the disk where you want to install macOS" and 2 disk icons: OS X Base System (499 GB) and Recovery
    HD (650 MB). BTW, sometimes after restarting second disk Recovery HD doesn't appear here[​IMG]
    7. When click on OS X Base System disk icon, it shows warning :"This disk is locked."

    8. If click on next icon with Recovery HD, it just shows what arrow with no label

    9. Anyway, Install -> button never gets enabled

    10. The only way too get out of this installation screen is to restart iMac

    11. After restarting and getting macOS Utilities, I go to Disk Utility

    12. Screen shows one Internal disk: ST3.....Media, when expand, shows disk icon OS X Base System
    13. If OS X Base System is selected, only first tab "First Aid" is enabled on Disk Utility, rest - Partition, Erase, Restore Unmount - are disabled. If running first aid, no errors shown up

    14. If disk ST3..... Media is selected, it enables also second tab Partition

    15 . From here you cannot click add(+) because it's disabled.. upload_2017-5-17_21-22-14.png

    Any help will be gratefully appreciated
  2. tdhurst macrumors 601


    Dec 27, 2003
    Phoenix, AZ
    Looks like you're starting up with the hard drive you want to reinstall the OS on.

    I believe you'll need to start up from the recovery or network drive, here's the key combos to hold during startup:
  3. Fishrrman macrumors G5


    Feb 20, 2009
    Get a USB flash drive, 16gb or larger.

    Create a bootable installer on the flash drive using either:
    1. Install disk creator
    2. Diskmaker X
    3. The terminal

    Boot from the installer flash drive.

    Re-initialize the internal drive (so you start "from scratch")

    Install onto the re-initialized drive.

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