Apple’s Worldwide Developers Conference to kick off June 10 at 10 a.m. PDT with Keynote address

The Keynote will be available to stream on apple.com, the Apple Developer app, the Apple TV app, and the Apple YouTube channel. On-demand playback will be available after the conclusion of the stream.

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vy185 Author

Level 1

4 points

Installation of MacOS

I reset my Mac to factory mode by enter recovery mode to erase my data on Macintosh HD. After that I clicked reinstall MacOS which is the Catalina. However, when looking at my disk utility afterward , I have two Macintosh HD -Data then I followed this post to try to make my Mac back to normal. But then when I power it off and try to enter the recovery mode again ... it didn’t let me and a cycle of a folder with a question then spinning glove . when I finally able to get to the recovery mode and try to reinstall my system . It say MacOS Seirra which then continues the error of not able to install it. Please help , do I need to bring my Mac to apple at this point? I don’t need to backup any data so my data recovery will not be a problem.

MacBook Air 13″, macOS 10.15

Posted on Oct 12, 2020 12:06 PM

Best reply

John Galt

Level 10

141,994 points

Posted on Oct 12, 2020 1:04 PM

The solution is to boot macOS Recovery again and use Disk Utility to completely erase the device.

Follow these instructions: Erase and reformat a storage device in Disk Utility on Mac - Apple Support.

Pay attention to Step 3. "The device" in its context refers to the entire storage device, meaning not a volume or partition subordinate to that device.

For the file system format select Mac OS Extended (Journaled).

Steps 1 and 8 are optional and inapplicable respectively.

Then, you should be able to install Sierra.

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Installation of MacOS

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