About support for encrypted Mac OS Extended disks in macOS 28 or later

In macOS 28 and later, the Mac OS Extended file system format will be supported only for volumes (disks and other storage devices) that aren't encrypted. For future macOS compatibility, either decrypt or reformat any encrypted Mac OS Extended volumes.

Check the volume’s format and encryption

Starting with macOS 26, your Mac might notify you that you’re using an encrypted Mac OS Extended disk and that it won’t be compatible with macOS 28 or later.

The notification will identify the volume by name, but if you want to confirm that the volume is using Mac OS Extended format and is encrypted:

1. Open Disk Utility, which is in the Utilities folder of your Applications folder. Or use Spotlight to find and open it.

2. From the View menu in the menu bar, choose Show Only Volumes.

3. In the sidebar of Disk Utility, select the name of the volume.

4. Look for the information shown directly under the name of the volume on the right. If you see both "Mac OS Extended" and "Encrypted" for your volume, that volume won't be compatible with macOS 28 and later. Example:

   • CoreStorage Logical Volume • Mac OS Extended (Case-sensitive, Journaled, Encrypted)

macOS 28 and later will continue to support unencrypted volumes that use Mac OS Extended format. Mac OS Extended is also known as HFS Plus (or HFS+).

Reformat or decrypt the volume

For any encrypted Mac OS Extended volume that you want to use with macOS 28 or later when it becomes available, back up any data that you want to keep, then take either action before installing the upgrade:

Reformat the volume

Erase and reformat the volume using APFS or APFS (Encrypted) format. This permanently deletes all data on the volume, but ensures future macOS compatibility.

Erase and reformat a storage device in Disk Utility

Or decrypt the volume

1. Connect the drive to your Mac and enter the encryption password when asked to unlock it.

2. Control-click the icon of the drive on the desktop or in the sidebar of a Finder window, then choose Decrypt from the shortcut menu that appears.

3. Enter the encryption password again when asked, then wait for decryption to complete. This takes time, especially for large volumes. To check progress, you can enter diskutil cs list in Terminal, which is in the Utilities folder of your Applications folder. Or use Spotlight to find and open it.

After decryption, you can optionally convert the volume to APFS format without erasing it:

1. Open Disk Utility, which is in the Utilities folder of your Applications folder. Or use Spotlight to find and open it.

2. From the View menu in the menu bar, choose Show Only Volumes.

3. In the sidebar of Disk Utility, select the name of the volume.

4. From the Edit menu in the menu bar, choose Convert to APFS, then click Convert to confirm. Quit Disk Utility when done.

5. If you want to encrypt the APFS volume, Control-click the icon of the drive on the desktop or in the sidebar of a Finder window, then choose Encrypt from the shortcut menu that appears.