It was reported last week that macOS Big Sur has a serious issue that can result in data loss when users try to upgrade a Mac to the latest version of the operating system without enough space available. The bug comes down to the macOS Big Sur installer not checking if the Mac has the required free space available to carry out an upgrade. The upgrade runs into problems, and if that isn’t bad enough, if the user’s Mac was encrypted using FileVault, then the user is locked out of their data. Apple has finally fixed the issue with a new build of macOS Big Sur 11.2.1, which properly checks if the disk has the required space before starting the upgrade process.
It was first reported that several users were getting an error message when upgrading a Mac computer to macOS Big Sur, which caused the Mac to no longer boot — and the only solution was to delete some files from the internal disk via Target Disk Mode (which doesn’t work for some models) or to wipe the entire disk.
Apple has finally released an updated macOS Big Sur 11.2.1 installer — (20D75) — that properly checks for the free space and does not allow the users upgrade the operating system without having enough space available. Unfortunately, this doesn’t seem to fix the Macs that got stuck after the macOS Big Sur installation started.