Upgrade to Big Sur. Access Denied.

Im trying to update my wifes macbook air to Big Sur but no matter what i do i get the message “could not complete. Access denied.”


i tried Disk Utility and doing a First Aid on both volumes.


Any ideas how to fix this?

Posted on Apr 16, 2021 1:50 AM

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Posted on May 4, 2021 2:48 AM

Shutdown computer by whatever means required. Disconnect all external Drives. Plug into charger. Restart and Immediately hold SHIFT. This will be Safe Mode and it will attempt to do a Repair Disk, clear cache files and only load Apple Software and Fonts. It will load slowly and is normal. The idea of doing the Safe Boot is to eliminate all Third Party software from interfering with the update process. If all goes well - it may or may not allow the installation to complete.

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Question marked as Top-ranking reply

May 4, 2021 2:48 AM in response to Pellehebsgaard

Shutdown computer by whatever means required. Disconnect all external Drives. Plug into charger. Restart and Immediately hold SHIFT. This will be Safe Mode and it will attempt to do a Repair Disk, clear cache files and only load Apple Software and Fonts. It will load slowly and is normal. The idea of doing the Safe Boot is to eliminate all Third Party software from interfering with the update process. If all goes well - it may or may not allow the installation to complete.

Apr 16, 2021 4:41 AM in response to Pellehebsgaard

How to upgrade to macOS Big Sur


macOS Big Sur is compatible with these computers


If upgrading from macOS Sierra or later, macOS Big Sur requires 35.5GB of available storage to upgrade. If upgrading from an earlier release, macOS Big Sur requires up to 44.5GB of available storage. To upgrade from OS X Mountain Lion, first upgrade to OS X El Capitan, then upgrade to macOS Big Sur.

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Upgrade to Big Sur. Access Denied.

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