Mike Bombich:

I remember seeing this one way back in Big Sur; you’d create a perfectly functional bootable copy of the system, but it wouldn’t show up in the Startup Disk Preference Pane. Apple ultimately resolved that issue in macOS Monterey, but now we’re seeing it again — unfixed in the Golden Gate release candidate.

The new CCC has a workaround, as does SuperDuper.

CCC 7.2 introduces a hybrid approach for bootable backups: as long as the source and backup OS versions are the same, CCC will update the backup incrementally without requiring any task configuration changes. This new approach will make many of the CCC-specific features available for bootable backup tasks, e.g. backup versioning, Quick Update, insight into what changes were made to the source between events. For the long stretches of time where your Mac’s OS isn’t getting updated every day, now you can enjoy the full benefits of the CCC backup solution.

These are great benefits for anyone that requires a bootable backup, but this isn’t a panacea. If the OS versions don’t match, the destination (and all backup versions) still must be erased and recloned; again, to offer the most reliably-bootable copy of macOS. We made improvements here, too. By default, CCC will ask for your approval before erasing the destination — this allows you to schedule your backup task without the fear of the backup getting automatically erased whenever the source OS is updated. That also allows you to retain the option of downgrading the source volume’s macOS, which you might want a day or so to assess.

Previously:

• macOS 27 Golden Gate
• SuperDuper 4
• Carbon Copy Cloner 7.1.3

Backup Carbon Copy Cloner Mac Mac App macOS 27 Golden Gate Startup Disk