Your Encrypted External Drive May Stop Working on macOS 28: What to Do Now
Your Encrypted External Drive May Stop Working on macOS 28: What to Do Now
Apple recently released a support document that sets a deadline for a portion of external drives: starting from macOS 28, expected next year, the operating system will no longer support volumes in Mac OS Extended format (also known as HFS+) when they are encrypted. Those who currently store data on an encrypted HFS+ external drive must take action before updating, or they will be unable to continue using it.
The wording of the document leaves no room for misunderstandings: from macOS 28, "Mac OS Extended format will only be supported for volumes (disks and other storage devices) that are not encrypted." Unencrypted HFS+ volumes will continue to work without issues even on macOS 28 and later versions: the cutoff only concerns the combination of the two elements—outdated format plus encryption.
How to Determine if a Drive is Affected
Starting with macOS 26, the Mac can display a notification when it detects an encrypted Mac OS Extended drive that is destined not to survive the transition, identifying the volume by name. Alternatively, the verification can be done manually through Disk Utility: by selecting the volume in the sidebar and reading the details beneath the name, if both "Mac OS Extended" and "Encrypted" appear together, the drive is among those affected. If only one of the two appears, there is no need to take any action.
Two Options Before the Update
To continue using an affected drive, Apple first recommends backing up data, then two possible actions. The first is reformatting: this erases the volume and recreates it in APFS or APFS (encrypted) format. It is the most straightforward option and ensures future compatibility, but it permanently deletes all data on the drive.
The second option is decryption, intended for those who want to keep the existing data. The drive is unlocked with the password, Decrypt is selected from the contextual menu in Finder, and the user must wait: Apple cautions that the operation takes time, especially on larger volumes. Once decryption is complete, the volume can be converted to APFS without deleting it, and if necessary, it can be encrypted again. One clarification is more significant than the others: this method does not apply to encrypted Time Machine backup drives, which must be managed differently.
The Rationale Behind the Move
Apple does not explain why it is intervening right now. However, the direction is consistent with a path that has been underway for years: APFS, the file system with integrated encryption, has replaced Mac OS Extended as the default format for Macs with High Sierra in 2017, and every subsequent step has progressively narrowed the space for the old format. Withdrawing support for encrypted HFS+ resembles a further step toward the definitive exit of a format that has its roots in 1998 when it debuted with Mac OS 8.1 as the successor to the original HFS.
For now, unencrypted HFS+ volumes remain supported, and Apple assures that they will continue to be supported even beyond macOS 28. The deadline only affects those who have combined the outdated format with encryption, and this audience should take action before next year's update.