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This copy of the Install macOS High Sierra application is damaged, and can‘t be used to install macOS

Unable to upgrade OS from Sierra to High Sierra..

iMac 27", macOS 10.12

Posted on Jan 21, 2020 10:36 AM

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Question marked as Top-ranking reply

Posted on Jan 21, 2020 10:41 AM

disconnect your clock and set the year somewhere between 2015-2017

then launch the installer again.

https://support.apple.com/guide/mac-help/set-the-date-and-time-mchlp2996/mac


6 replies

Jan 21, 2020 11:52 AM in response to AppleDisciples

Open your Application folder, locate Install macOS High Sierra.app, move it to the Trash, empty the Trash.

Connect your mac to your router using a cable rather than rely on WiFi. Restart your Mac go back to the App Store High Sierra

page and press Get. The download should start, do not use your mac while it is downloading and if any other devices share the same internet connection don't use them either.

Jan 21, 2020 11:10 AM in response to JimmyCMPIT

After changing the date, I'm unable to launch the installer due to invalid certificates. I attempted the years 2015, 2016 & 2017. Below is the message:


Websites prove their identity via certificates, which are valid for a set time period. The certificate for support.mozilla.org will not be valid until 6/12/2019.


Error code: MOZILLA_PKIX_ERROR_NOT_YET_VALID_CERTIFICATE

This copy of the Install macOS High Sierra application is damaged, and can‘t be used to install macOS

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