You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

User profile for user: Kamau10
Kamau10 Author
User level: Level 1
4 points

MacBook Pro won’t restart after trying to instal Big Sur

I recently updated to Big Sur, but immediately after the 12.(something) GB update had finished it stated that I must restart the system - so I did. It then showed the normal Apple logo with the loading bar below it with “About 25 minutes remaining...” After about an hour it still hadn’t loaded and then appeared a small box which read “An error occurred preparing the software update.” After clicking okay, there was a larger box which stated that I needed to “Choose Startup Disk,” but only gives the option to “start the computer in target disk mode,” which only allows the computer to be used as a hard disk for another computer with the use of a thunderbolt cable.


I have tried restarting and shutting down the system several times yet the same issue continues to happen. I can’t access or use the computer to any extent beyond what I just mentioned... any suggestions/advice would be HUGELY appreciated.


(Screenshots attached below)


MacBook Pro 13″, macOS 10.14

Posted on Feb 4, 2021 7:59 AM

Reply

Similar questions

1 reply
User profile for user: Joseph_S.
Joseph_S.
User level: Community Specialist

Feb 7, 2021 9:07 AM in response to Kamau10

Hello Kamau10,


Thanks for using Apple Support Communities! We understand you are encountering some problems after trying to update your Mac to macOS Big Sur and how are unable to start up your Mac. We are happy to help provide some guidance.


Since there seems to be an issue with picking your startup disk at this point during the upgrade process, we would recommend that you boot the Mac up in to macOS Recovery and try reinstalling macOS Big Sur again, or reinstalling the latest macOS version that is compatible with your Mac. Take a look at the steps on how to do that here:


How to reinstall macOS


We also want to make sure that you have enough storage space available to install macOS Big Sur. If upgrading from macOS Sierra or later, than you would need to have at least 35.5GB of storage available. If upgrading from an earlier version of macOS, you would need 44.5GB available.


Keep us updated on how it goes or if you have any questions along the way. We hope this information helps.


Best Regards.

Reply

MacBook Pro won’t restart after trying to instal Big Sur

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.
Learn more Sign up