Your Mac was unable to communicate with your Apple Watch.

Hi all,

I recently starting having this issue around when I updated to Big Sur and have been ignoring it until today.

What I did unpair and repair my phone.

First, do a backup (I backed mine up to my laptop, I think you can do iCloud as well, but I prefer a hard backup) of your iphone to your mac.

Next, I unpaired my watch, which basically resets it back to factory default.

On the Mac, I opened Keychain Access and deleted the files noted in mark_t's comments (in addition to the passwords for apple watch). Then I deleted the preferences per his instructions and restarted my mac.

On the watch, I re-paired my watch to my iPhone.

Once re-pairing was complete, I went into preferences, security and privacy- and clicked on the option to unlock. It failed the first time, but was successful the second time.

Hope that helps someone here.

got it. just activating unlock boxes in ALL the computers in my icloud, included the one not updated because of the summer time.

In my case, the issue went away with the recent update to Watch OS 7.1

With the installation of WatchOS v7.1, both of my 2018 i9 MBPs unlock with my Watch 4. It appears Apple identified the issue.

unpairing, and setting it back up from a backup did it for me.

Hi, I couldn't find the .plist files anywhere in my Mac, the KeyChain Access stuff I did however. I tried restarting anyways and on the second go at connecting it finally works!

I am on Macbook Air 2017, running High Sierra 10.13.6. Apple Watch SE, running WatchOS 7.0.1

Thanks!

I had this issue before and back then the deletion steps outlined here a couple of times (keychain items etc) worked back then, but this time they didn't.

A simple log out of iCloud on the Mac and back in did the trick this time.

I tried all of the listed solutions. What finally worked for me was unpairing my Series 5 Cellular Apple Watch with my iPhone 11 Pro and then pairing and syncing the Apple Watch from backup. After that, selecting the option to: Use your Apple Watch to unlock apps and your Mac failed on the first try and then worked flawlessly on the second try. Hopefully it will continue to work in the future.

I have had this same issue and had no luck with any of the solutions I found in this thread. What finally worked was unlocking my watch AND my iPhone, then selecting "Use your Apple Watch to unlock apps and your Mac."

My watch stopped unlocking my Macbook Air after upgrading phone to iPhone 12 last week and having to re-pair Watch Series 4, but it would still allow me to double-tap the side to authenticate all other touch id functions. I followed the steps in the earlier post but didn't seem to work. So, restarted all my devices, followed the steps again making sure my watch was on and on my wrist and that my iPhone was unlocked. Received an error message twice but not the third time (the charm?). Then, restarted everything again.

Now it's unlocking my macbook AND authenticating other touch id functions on my macbook

fiiiiiinally..

This worked for me too.. But had to add in step 11a: restart your mac

After a reboot is was finally able to re-enable unlock with watch.

Go to search and type Keychain Access.

The newest iOS update fixes it. The update came out last week. Update your iPhone and watch iOS.

So - same thing happened to me after repairing my watch after watchOS 7 update

I did get it to work - following mark__t's advice.

It didn't work initially or after a reboot - so I wandered off for a while.

When I came back the MacBook had locked - when I put in the password it unlocked and I had a popup from the notification area effectively saying 'did you know you can use your Apple Watch to unlock your MacBook'

I thought that this is just rubbing salt into the wounds but hit 'turn on' anyway.

It opened system preferences and asked for my password - I entered it, ticked the box and after the now-familiar spinning it turned on...

Thanks for your help