"An Error occurred while preparing the installation [Sierra]"

This is a discussion on "An Error occurred while preparing the installation [Sierra]" within the Mac OS X forums, part of the Mac Software category; Hi there. I'm attempting to reinstall Sierra OS on my 2012 MacBook Pro.( I've done a full back up on an external drive using time ...

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Thread: "An Error occurred while preparing the installation [Sierra]"

  1. #1
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    "An Error occurred while preparing the installation [Sierra]"

    Hi there.

    I'm attempting to reinstall Sierra OS on my 2012 MacBook Pro.( I've done a full back up on an external drive using time machine.)

    Issue: With 20 seconds remaining, the install fails and I get this message:

    "An Error occurred while preparing the installation."

    Most on-line discussions I've looked into on this particular issue reference the wrong date/time as a cause for the problem. The fix is simple - go into Terminal and correct the date/time (writing it in a specific and precise format) which I have done.

    Prior to this point, the install attempt begins with me shutting down the Mac, then holding down the power button while simultaneously holding down Command-R. (I've also tried this method while holding Option-Command-R - an alternative option for a slightly different version of the OS).

    In all cases, the install fails, with the same error message as above.

    So, if the issue is generally deemed to be the time/date, and yet the time/date has been corrected through Terminal (Terminal accessed within 'macOS Recovery'), then my question is:

    What is the solution to get past the error message? What is the next step or option?

    Currently, and since attempting to reinstall Sierra OS, the MacBook will not reboot, not even in safe mode.

    Any suggestions or guidance would be gratefully received.

    I apologize in advance if I haven't provided appropriate technical information. I will happily provide any additional information that is required.

    Thanks and regards,

    Sean


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  3. #2
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    Hi Sean. Are you trying in reinstall Sierra from the Recovery partition?
    'Deep Thought' - Mac Mini Late 2014 - macOS Sierra (10.12.4)
    'Orac' - MacBook Pro 13" Mid 2012 - macOS Sierra (10.12.4)
    'Marvin' - Hackintosh - Mavericks Server (10.9.5)
    'Holly' - Hackintosh - Mavericks Server (10.9.5)

    iPhone 6S - iOS 10.3.2
    iPad Pro 12.9" - iOS 10.3.2

  4. #3
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    To be honest my Knowledge base is such that I can't answer that! I'm installing in Mac OS Recovery which I accessed by holding 'Command-R' while rebooting after shutting down. Cheers.


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  5. #4
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    Well, like you the only reference to this error seems to be related to date/time issues. It would appear you have a corrupt recovery partition. The only way I can see you being able to perform a clean install is if you have access to another Mac ? If you do, you can download a copy of the Sierra installer from the Mac App Store and create a bootable USB stick to install from. See instructions here : http://lifehacker.com/how-to-make-a-...ive-1786853248
    J. A. likes this.
    'Deep Thought' - Mac Mini Late 2014 - macOS Sierra (10.12.4)
    'Orac' - MacBook Pro 13" Mid 2012 - macOS Sierra (10.12.4)
    'Marvin' - Hackintosh - Mavericks Server (10.9.5)
    'Holly' - Hackintosh - Mavericks Server (10.9.5)

    iPhone 6S - iOS 10.3.2
    iPad Pro 12.9" - iOS 10.3.2

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