Apple Patches Bug Hindering Bootable Backups with macOS 15.3 Update

Apple has resolved a bug in macOS Sequoia 15.3 that prevented utilities like SuperDuper! from making bootable backups. Developer Dave Nanian reported the issue in December 2024, noting that the problem occurred during the replication of the Data volume and caused a Resource Busy error. The fix means that 'Erase, then copy' backups will work again without requiring an update to SuperDuper!. However, this does not guarantee successful booting from the backup in all cases. Additionally, Apple has been making it increasingly difficult to start up Macs from external drives for privacy and security reasons, especially on Apple Silicon Macs with Signed System Volumes.