PSA: macOS 28 will drop support for encrypted Mac OS Extended volumes

PSA: macOS 28 will drop support for encrypted Mac OS Extended volumes

Apple has announced that macOS 28 will end support for encrypted Mac OS Extended volumes. According to a new support document, the Mac OS Extended file system format will be supported only for disks and other storage devices that are not encrypted starting with the release of macOS 28, which is expected in 2027.

This change means users relying on encrypted HFS+ external drives or other legacy Mac-formatted volumes will find them incompatible with the operating system unless they decrypt or reformat the drives before upgrading. Apple has not provided a specific reason for the move, though it follows the introduction of the Apple File System (APFS) in 2017 with macOS High Sierra. APFS, which natively supports encryption, was designed for the SSDs that are now standard in every Mac, while the Mac OS Extended (HFS+) format was introduced in 1998 for hard drives and Fusion drives.

The transition to the newer format is already underway. Apple previously announced the deprecation of encrypted Mac OS Extended in the developer notes of the macOS 27 beta. Furthermore, Apple states that starting with macOS 26, Macs may notify users when an encrypted Mac OS Extended disk is detected that will not be compatible with macOS 28 or later, identifying the specific volume by name.

Users can manually check their drive compatibility via Disk Utility. A volume is incompatible if the format details listed beneath its name show both Mac OS Extended and Encrypted, such as CoreStorage Logical Volume • Mac OS Extended (Case-sensitive, Journaled, Encrypted).

Options for Affected Users

Apple recommends backing up all data before attempting to modify a volume. Users have two primary paths to maintain compatibility:

• Reformatting: Users can erase the volume and reformat it using APFS or APFS (Encrypted) format. This ensures future compatibility but permanently deletes all existing data on the volume.
• Decryption: This allows users to preserve existing data. The process involves connecting the drive, unlocking it with the encryption password, and choosing Decrypt by Control-clicking the icon in the Finder or on the desktop. Apple warns that decryption takes time, especially for large volumes, and notes that progress can be monitored in Terminal.

After decryption, users have the option to convert the volume to APFS without erasing it using the Convert to APFS option in Disk Utility, then re-encrypt it if desired.

Special Considerations for Backups and Archives

Apple specifies that the decryption path does not apply to encrypted Time Machine backup disks. Because older HFS+ backups rely on directory hard links that are unavailable in APFS, there is no way to convert or migrate those backups to the newer format. Users must close and archive current backups and start new backup series on fresh APFS storage.

For those with long-term archives on encrypted HFS+ volumes that are seldom accessed, some suggest retaining an old Mac capable of running macOS Golden Gate or earlier to maintain access. However, warnings exist regarding the reliability of hardware for long-term storage; hard disks can suffer from physical and magnetic degradation, and SSDs may be prone to loss of charge.

Alternative archival suggestions include the use of archival tapes or Blu-ray optical discs, specifically M-DISC products. These require storage in dark, dry, and cool conditions and periodic integrity checks to ensure data remains intact.

While macOS 28 ends support for encrypted versions of the legacy format, Apple confirmed that unencrypted volumes using Mac OS Extended (HFS+) will continue to be supported in macOS 28 and later versions.