Unable to install Mac OS High Sierra on 2011 iMac

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Unable to install Mac OS High Sierra on 2011 iMac

Background:

I have a 2011 iMac whose hard drive died. I replaced to drive with a new SSD drive. Everything otherwise seems successful, but I cannot reinstall the operating system.

What I have tried so far:

1) Resetting NVRAM/PRAM;

2) Starting with recovery from internet option (I get the spinning globe, but nothing happens beyond that. My guess is Apple is no longer supporting this option for this old operating system or desktop);

3) Starting with good USB stick with High Sierra I've used in the past, and attempting to install the OS from there. It states that the install is "damaged" and cannot continue. I tried creating another USB stick with High Sierra, and it also has the same error;

4) Starting without any USB stick just gives me a blinking question-mark folder (understandably).

Note: the new internal hard drive can be seen in the disk utility, and has been formatted APFS.

Any suggestions on how to proceed?

Posted on Dec 31, 2021 4:03 PM

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Answer 1

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mk553 Author

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Jan 1, 2022 10:57 AM in response to rkaufmann87

In case anyone else has this problem and needs the solution:

Turns out, the "This copy of the install macOS High Sierra application is damaged, and can't be used to install macOS" has to do with an expired codesign certificate. Some sites suggested downloading a new copy, but it doesn't appear this is possible any longer.

At any rate, the fix was to drop to the Terminal/command prompt after booting up with the High Sierra USB stick, and set the clock back:

date 010100002018 (other dates are required for other versions of the operating system).

Then I was able to select "Install OS..." and proceed from there.

Sometimes Apple makes this very easy, and sometimes they make it very hard...

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