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MacBook won’t start with Mac OS: Mac partition disappeared

Hi I have a MacBook Pro and tonight I was updating my OS High Sierra. While updating. There was black screen saying updates needs “about 30 mins”. It remained stuck there with no progress for a long time. I turned it off and back on and now it only logs into Windows which I had installed using bootcamp. My Mac OS partition does not show. When I press the “option” button to it only shows the windows hard drive. When I tried try to restart from Bootcamp to restart OS X, it restarts but sends back to Windows. I now don’t know if my Mac OS is updating or if it’s gone and what to do next. When I press Command + L while in Windows it does nothing. If I try as soon as I restart the computer and before Windows loads, it also does nothing.


Highly appreciate your support.



MacBook Pro 13″, macOS 10.12

Posted on Sep 7, 2020 1:52 PM

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Question marked as Top-ranking reply

Posted on Sep 7, 2020 9:04 PM

Try to boot into Recovery Mode (Command + R) or Internet Recovery Mode (Command + Option + R) so that you can run Disk Utility First Aid on the drive.


I highly recommend you have a good backup of your Windows data before you do anything else just in case Windows becomes unbootable while you attempt to repair macOS.

2 replies

MacBook won’t start with Mac OS: Mac partition disappeared

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