An error occurred preparing the software update - Big Sur
I tried to do the Big Sur update and near the end of the installation i get the message
"An error occurred preparing the software update "
and then i'm asked to select a startup disk.
I've tried rebooted a few times and it always happens.
I assume i'll need to do a recovery of some sort.
I tried to reboot with CMD+r and then i was asked to enter the user password, which wasn't accepted (even through it's definitely the correct password).
Can anyone suggest what i should do next?
MacBook Air