Trying to erase disk in iMac ... get message

Get message

unmounting disk

couldnt open device .. (-69877)


operations failed

Posted on Jan 27, 2021 7:00 PM

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Posted on Jan 27, 2021 8:18 PM

What year model iMac?

Identify your iMac model - Apple Support


You have to startup from a different disk. It can be the original Install DVD, an external startup disk or macOS Recovery Mode depending on the year model.

How to erase your Intel-based Mac - Apple Support

3 replies

Jan 28, 2021 7:38 AM in response to Javedoo

You're welcome.


You bought it used or new from Apple?


If it is used, you may have trouble if the previous owner did not properly prepare it for resale.

What to do before you sell, give away, or trade in your Mac - Apple Support


If it is new, then you need to use macOS Recovery Mode to erase and reinstall macOS.

About macOS Recovery on Intel-based Mac computers - Apple Support

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Trying to erase disk in iMac ... get message

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