macOS 28 drops encrypted HFS+ support, prompting decrypt or reformat to APFS
Apple’s macOS 28 will drop support for encrypted Mac OS Extended (HFS+) volumes, so encrypted HFS+ drives must be decrypted or reformatted to APFS to continue functioning. Unencrypted HFS+ volumes remain supported. Users should back up data first and can either decrypt and then convert to APFS or reformat the drive to APFS (Encrypted or not) via Disk Utility; note that encrypted Time Machine backups aren’t covered by this guidance.