Apple Drops macOS 28 Support for Encrypted HFS+ Volumes as APFS Transition Deepens

Q: With macOS 28 making older encrypted backups inaccessible, are users facing the permanent loss of their archived data?

No. macOS 28 does not automatically erase archived data, but it will make encrypted HFS+ volumes unreadable on Macs running that version or later unless users act beforehand. The affected disks are older Mac OS Extended (HFS+) volumes that are also encrypted, typically using CoreStorage. Apple will continue supporting unencrypted HFS+ volumes, but encrypted ones will lose compatibility as Apple completes its shift to APFS, which has native encryption. For most encrypted HFS+ external drives, the data can be preserved by decrypting the volume before upgrading, then optionally converting it to APFS and re-encrypting it in APFS format. Reformatting to APFS is another path, but that wipes the disk and requires a full backup first. The biggest risk is with encrypted HFS+ Time Machine backups. Those cannot simply be decrypted and converted in place. Users will generally need to keep the old backup as an archive and start a new Time Machine backup set on an APFS-formatted disk. That means the old backup is not necessarily lost, but it may only remain accessible on an older Mac that still supports encrypted HFS+. Apple is expected to begin warning users in macOS 26. Anyone with long-retained external archives or backup drives should check Disk Utility now for volumes labeled both “Mac OS Extended” and “Encrypted.” The practical takeaway is urgency, not inevitability: users who migrate or decrypt in time can keep their data; users who do nothing risk losing access on newer Macs.

3 articles · Updated · 9to5Mac · Jul 8

macOS 28 will no longer mount encrypted Mac OS Extended—HFS+—volumes, forcing affected users to decrypt them or erase and reformat them to stay compatible.
Apple gave no reason, but the change extends its shift to APFS, which became the default Mac file system in macOS High Sierra and includes built-in encryption support.
macOS 26 may start warning users about incompatible encrypted HFS+ disks by volume name, and unencrypted Mac OS Extended volumes will still be supported in macOS 28.
Apple says users can verify affected drives in Disk Utility by checking for both “Mac OS Extended” and “Encrypted”; encrypted Time Machine backup disks cannot use the decryption workaround.
For longer-term compatibility, Apple recommends backing up data first, then either decrypting the volume and optionally converting it to APFS or reformatting it directly as APFS.