Apple quietly published a support document this week warning users that macOS 28 will drop support for encrypted Mac OS Extended (HFS+) volumes entirely.
For the vast majority of Mac users, this is a non-event. But those who rely on traditional spinning hard drives, or HDDs, for storage or backup will want to listen up, because some commonly accepted sage advice is in need of updating as a result of this change.
HFS+ vs. APFS
To be clear, Apple isn’t ending support for the HFS+ file format outright. According to the support document, macOS 28 and later will continue to mount and read unencrypted Mac OS Extended volumes without issue.
This change targets a much narrower case: any HFS+ volume that’s also encrypted. Once macOS 28 arrives, those drives simply won’t mount until you decrypt or reformat them.
Apple hasn’t given an official reason for the change but it seems like another step in the company’s transition away from HFS+ to its current file system format APFS. You can read more about APFS and HFS+ in our file format explainer here, but the short version of the history of these two formats is that APFS replaced HFS+ as the default Mac file system back in 2017 with the release of macOS High Sierra. APFS was built with modern computing in mind, prioritizing SSDs, native encryption, snapshots, and dynamic space sharing between volumes. Released in 1998 alongside Mac OS 8.1, HFS+ was simply a file system from a bygone era and was never designed to handle these features.
As a result, FileVault encryption on HFS+ has always been something of a workaround, relying on an older Core Storage layer rather than native file-system-level encryption. Retiring it removes one of the last dependencies on that legacy layer.
Apple says Macs running macOS 26 Tahoe may already start warning users when an incompatible drive is connected, naming the affected volume directly. You can also check manually: open Disk Utility, select a volume, and look at the description beneath its name. If it reads something like “Mac OS Extended (Case-sensitive, Journaled, Encrypted),” that drive won’t mount when macOS 28 ships.
How to Prepare an Affected Drive for macOS 28
Before touching anything, back up whatever’s on the drive. From there, you have two paths, both outlined in Apple’s support document:
- Reformat the volume as APFS or APFS (Encrypted) through Disk Utility. This is the cleanest option, but it erases everything on the drive first — hence the backup.
- Decrypt in place, without erasing. Connect the drive, unlock it with your password, then decrypt through Disk Utility (you can track progress with “diskutil cs list” in Terminal for large volumes). Once decrypted, you can optionally convert it to APFS without losing data, then re-encrypt as APFS Encrypted afterward. To see the full decryption instructions, check out the Apple support document here.
One exception worth knowing: this process doesn’t apply to encrypted Time Machine backup disks, which follow their own rules.
I Thought APFS Didn’t Work Well on HDDs?
Here’s where this gets a little ironic for longtime Mac users. For years, the standard advice was to format all HDDs as Mac OS Extended rather than APFS. While HFS+ was introduced at a time when the majority of drives in use were spinning HDDs, APFS wasn’t optimized for those spinning platters; it was designed with SSDs in mind, and its behavior on traditional HDDs could be inconsistent, with reports of sluggish performance and directory-listing quirks.
APFS relies on copy-on-write, meaning changed files get written to new blocks rather than overwritten in place, and unlike HFS+, it stores file metadata scattered alongside file data instead of in one fixed location. On an SSD, that doesn’t impact performance one iota. On a spinning HDD, however, it means the drive’s read/write head has to physically seek around to reassemble files and metadata. All of that movement and seeking can cause performance of the drive to degrade — sometimes severely — the more a volume gets written to and changed.
This performance cost shows up most on actively-used working drives and, notably, on Time Machine volumes that see constant incremental writes; it’s much less of an issue on a drive that’s written once and mostly just read afterward.
As a result, HFS+ was and still is the best format for HDDs. If you format an HDD in APFS even today, you’re still going to get fragmentation.
The good news, as we explained above, is that even after this change you’ll still be able to format HDDs in HFS+ and have them mount with macOS moving forward. You just won’t be able to also encrypt those drives.
So What Format Should I Choose for an HDD Now?
For an external HDD on a Mac today, the decision really comes down to one question: does this drive need to be encrypted?
- If yes, use APFS (Encrypted). With encrypted HFS+ on its way out, APFS Encrypted is the only supported path forward for an encrypted spinning drive. Just go in aware of the tradeoff: APFS’s copy-on-write design means a drive that gets written to and changed often can fragment and slow down over time on a spinning disk.
- If no, stick with HFS+ (Mac OS Extended). Nothing about this change affects unencrypted HFS+ volumes, and its simpler, fixed-location metadata still holds up better on spinning disks than APFS does. If you don’t need encryption, there’s no reason to move off it.
- Time Machine drives should be left on APFS and managed automatically by macOS — Apple has tuned that specific workflow for years, and Time Machine has required APFS for new backups since Big Sur.
