“Your Mac was unable to communicate with your Apple Watch”: How do I fix this?

One feature added to MacOS a few years ago was the ability for Apple Watch owners to use it as a way to unlock Macs. It’s a great feature, too. It’s just… temperamental. One such problem is the error “Your Mac was unable to communicate with your Apple Watch”.

There are many, many articles dedicated to various obscure things that may or may not resolve this. But if you’ve just upgraded your Apple Watch, this is definitely worth a shot. It’s quick and, unlike other possible solutions, it’s non-destructive.

How to switch on the ability for your Apple Watch to unlock your Mac

• On your Mac, head into System Preferences
• Open Security & Privacy and then click on the General tab
• The third option is named Use your Apple Watch to unlock apps and your Mac
• Ensure this option is ticked

If the error “Your Mac was unable to communicate with your Apple Watch” appears after you tick this, then read on.

Have you just upgrading your Apple Watch?

If the answer is “yes” then I may have the answer for you.

1. On your Mac, head into System Preferences > Apple ID
2. In the bottom left of the window, all of your devices are listed
3. Look for your old Apple Watch
4. If it’s there, click on it and then hit Remove from account (make sure you’re definitely finished with the old Watch first)
5. Return to the Apple ID screen and make sure your old Watch has been removed from the refreshed list
6. Head back to Security & Privacy > General and try ticking “Use your Apple Watch to unlock apps and your Mac”

Hopefully, it should now work.

Why does this work?

There is no official answer on this, but this is my best guess. When you switch the feature on, it doesn’t ask which watch you want to use if you have more than one, so I can only assume it just plumps for the first one that it comes across. If you have more than one Watch on your account and the first one listed is one that you are no longer using then, yes, your Mac isn’t going to communicate with your new device. By removing the old Watch and making your new one the only one listed, it connects correctly.

What if this doesn’t work?

If this doesn’t work then, yes, there are lots of possible solutions.

Sometimes restarting your Mac and Watch are sufficient. If that fails, you can try the following (links lead you to third-party sites that will take you through the process):

• Remove Auto Unlock settings from Keychain
• Reset Bluetooth and Wi-Fi on both devices (watch and Mac)
• Switch off Handoff on your iPhone and turn it back on
• Sign out of iCloud on your Mac, then sign back in

The first one is pretty complex but appears to fix the problem for a lot of people. The others are all quite easy but the last one is more painful, in that it causes all of your iCloud content to disappear and then re-download again (I’d leave that one to last!).