iMac M1: WD My Passport compatibility warning for macOS 28

fsoares wrote:

I am getting a warning about WD compatibility with macOS 28 in my iMac M1 (OS 27.1)

I use My Passport with an external 2TB WD disk for automatic backups.

The WD site does not offer any clue. What can I do?

If you are ‘seeing a WD My Passport compatibility warning on your 2021 M1 iMac running macOS 27.1, don't panic or rush to replace your 2TB WD external drive. The warning may relate to the disk's format or encryption rather than the drive itself.

Apple has announced that encrypted Mac OS Extended (HFS+) disks will no longer be supported in macOS 28 and later. Your Mac may warn you about this in advance.

You can read Apple's explanation here: About support for encrypted Mac OS Extended disks in macOS 28 or later.

First, check your WD drive

Open Finder >> Applications >> Utilities >> Disk Utility. Select View >> Show All Devices, then click the volume you use for backups and check its format.

If it says Mac OS Extended (Journaled), Encrypted, this may explain the warning. If it says APFS or APFS (Encrypted), this particular compatibility issue should not apply.

Apple's Disk Utility User Guide explains how to check your disk's details.

What if you use Time Machine?

If your WD drive is used for Time Machine backups, don't erase or reformat it just to get rid of the warning. You could lose your existing backup history.

Apple's instructions for converting or decrypting ordinary encrypted disks do not apply to encrypted Time Machine backup disks. If your drive uses that format, the safest approach is to prepare another backup disk and establish a new backup before changing anything on the existing one.

See Apple's guides to choosing a Time Machine backup disk and backing up your Mac.

What if you use WD backup software?

If your backups are managed by WD Backup, WD SmartWare, or another WD application, the issue may be the software's compatibility with newer versions of macOS rather than the drive itself.

Before making any changes, check whether the warning refers to the WD application or to the disk's format. These are two different issues.

If you decide to reformat the drive, first copy your important files elsewhere and verify that the copies are accessible. Reformatting erases the selected volume. Apple's instructions are here: Erase and reformat a storage device.

My advice

I'd stay on macOS 27  for now while checking the warning, rather than rushing into an upgrade. Your 2TB WD My Passport may still be perfectly usable; you may simply need to change your backup method or move to a supported disk format.

The most important thing is to protect your existing backups before making any changes.

One question that would help narrow this down: Open System Settings → General → Time Machine. Is your WD My Passport listed there as your backup disk, or do you use a separate WD application to manage your automatic backups ?

A warning is triggered when you launch an Intel-only app, and you will see it every time you launch such an app. Launching a recently used Intel app again won't trigger it, but if enough time has passed then you'll see the warning again for that app. For example, I last used the SynologyAssistant app to check on my NAS over a month ago, and launching it generated the banner message.

To avoid this issue you need to run only Universal or Apple Silicon apps. For apps that are Intel only, contact the developers and push them to release updated versions of their apps (but keep in mind that they have over a year before their apps stop working on macOS). 

To see which of your apps are Intel and thus need to be updated or they won't run on macOS 28 (Fall 2027), hold the Option key and click the Apple menu, then select System Information (the top item). Select Applications in the Software section of the sidebar, then click on the Kind column header to sort them. 

Some apps aren't readily identifiable by the name, but when you select that app you will get more info. For example, 'commandFilter' is a component of the Epson printer drivers. Apps like that can be safely deleted. 

Here's what Apple has to say about updating your apps:

Learn how to update Intel-based apps for Apple silicon - Apple Support

fsoares wrote:

The format shown is “APFS (Case-sensitive)”.

My Passport is listed as my backup disk in Settings->General->Time Machine. 

The warning I got (in the upper right corner of my screen) referred to the WD application. 

Uninstall the WD application or ignore it. The app will not work on macOS 28. If you are using Time Machine with that drive, the app is doing nothing.

Never install the software bundled with a drive. It is all useless and causes problems. If a drive needs special software to make it work correctly, return it and buy another.

What's the warning?

If it's this one

then it's because the disc uses Apple File Protocol (AFP) which is deprecated and, if possible, you need to change the file access mode to SMB.

If it's something else then a screenshot would be helpful.

fsoares wrote:

The warning I got (in the upper right corner of my screen) referred to the WD application. 

That would answer the question

Using Time Machine Backupwithout the need for Third Party Manufactures Third Party Software

The format shown is “APFS (Case-sensitive)”.

My Passport is listed as my backup disk in Settings->General->Time Machine. 

The warning I got (in the upper right corner of my screen) referred to the WD application.