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Mac OS installation error

Whenever I try to reinstall Mac OS on my Mac a soon as it’s about to finish the time remaining says -399 seconds remaining and then an error message pops up at the top saying “An error occurred while preparing the installation. Try running this application again” and I did that but it still says the same thing

Posted on Sep 11, 2021 9:18 AM

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Posted on Sep 12, 2021 7:45 AM

https://bensmann.no/changing-system-date-from-terminal-os-x-recovery/


This refers to changing the date of the computer via Terminal. The Apple Certificate embedded in the Sierra Installer might have expired.

2 replies

Sep 12, 2021 7:40 AM in response to itsyaboiale10

Hi itsyaboiale10, We appreciate you reaching out to us. We understand that you are experiencing issues in reinstalling macOS Sierra.


We’d like to gather additional details that may help us be in a better position to assist you. Would you please tell us the exact year and model fo your device?

Would you please tell us which method you are using to reinstall macOS? For example, are you using internet recovery or are you using a bootable installer?

If you are using internet recovery, have you had the chance to try a different network to complete the task?

If you are using a bootable installer, have you had the chance to use a different flash drive and a different download of the installer?


In the meantime, the article below may provide some insights.

How to reinstall macOS


Take care!

Mac OS installation error

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