An error occurred loading the update - Big Sur installation
Hi everyone,
Tried to update my wife's Air A1932 to Big Sur in a normal way from System Preferences/Software Update.
In the middle of installation getting an error 'An error occurred loading the update'.
Mac boots into recovery, choosing 'Reinstall Big Sur' results into the same error, did it 20 times already.
I've created bootable USB installer on my second Mac, connected it to this one, but receiving 'Security settings do not allow this Mac to use an external startup disk'
Rebooted into Recovery, launched Startup Security utility, and get 'No administration was found'
Two days of reading forums, trying, and failing.
Wiping the disk isn't an option, I can't lose data.
Any help with restoring Catalina or installing Big Sur would be highly appreciated!
MacBook Pro 13″, macOS 11.1