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Unable to install the MacOS Big Sur upgrade

I have a 2019 MacBook Pro [with Catalina]. Each time I attempt to install the Big Sur upgrade I receive this msg "An error occurred installing macOS. [and] You can try again to complete the installation." I have tried to install at least 30 times, and using a variety of methods [Safe Mode, Recovery, from different sites, and with a new Admin user]. It's always the same. Has anyone experienced the same?

MacBook Pro 13″, macOS 10.15

Posted on Dec 4, 2020 7:36 AM

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Question marked as Top-ranking reply

Posted on Dec 4, 2020 7:49 AM

Apple requires that you have 35.5 GB of available space on the installation drive before you even think about performing the upgrade to Big Sur.


I actually booted into Safe Boot mode, before rebooting into Recovery, and ran Disk Utility First Aid on my startup drive — followed by a normal reboot. I then perfomed one last Time Machine backup, and ensured that I had 50GB of available storage, just for good measure. My Big Sur upgrade was uneventful and successful.

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Question marked as Top-ranking reply

Dec 4, 2020 7:49 AM in response to 23Nov2020

Apple requires that you have 35.5 GB of available space on the installation drive before you even think about performing the upgrade to Big Sur.


I actually booted into Safe Boot mode, before rebooting into Recovery, and ran Disk Utility First Aid on my startup drive — followed by a normal reboot. I then perfomed one last Time Machine backup, and ensured that I had 50GB of available storage, just for good measure. My Big Sur upgrade was uneventful and successful.

Unable to install the MacOS Big Sur upgrade

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