Has anyone experienced this when updating a Mac to OS Big Sur?

Question

macOS

The Mac was updated on Big Sur, everything was fine, there was enough memory for the update. Upon completion, this error appears, when you click "OK", it is proposed to use the poppy in external disk mode. When rebooting, the update starts from the same place (approximately from the middle, it says that 29 minutes are left), upon completion, this error occurs again. How to be?

Answer 1

This is a Big Sur bug that apple has acknowledged.
Reboot immediately, during or before the beep, hold down the Command and R keys until the Utilities menu appears.
Select Disk Utility and click the Continue button.
Then select the indented volume entry (usually Macintosh HD) from the side list.
Click the "First Aid" tab on the toolbar and wait for the "Finish" button to activate. Click it, then exit Disk Utility.
Choose Restart from the Apple menu.
I advise you to update only with the power connected.