Your Mac was unable to communicate with your Apple Watch.

I used the 12-step solution provided by @mark__t and it worked quite well. The only slight change I made is that in step 9, I used the Terminal app to navigate to ~/Library/Sharing/AutoUnlock, and I first (quite unsuccessfully) tried the disable/enable keychain solution. Other than that, thank you @mark__t!

Any update on this issue? I'm having the same issue as well and tried everything above.

My setup is an Apple Watch 4 with Watch OS 7.0.2 and MacOS 10.15.7 on a Mid 2015 MBPwRD.

Thank you for any updated info.

I had to do the fix a few weeks a go when I upgraded to watch os 7 on a series 3. Since then I've changed my series 3 to a new series 6 and it worked first time without having to do the fix again on the iMac

My partner who also changed from a series3 to a series 6 at the same time did have to re do the fix on the MacBook. Can't explain that!

The method originally posted by mark_t works perfectly though.

Worked for me. The search for "Sharing/Unlock" worked but not the search for "~/Library..." as per Mark_T. Thank you very much TiggerGTO and Mark_T. Now only to wonder why this happened and if it will happen again. High hopes!

I tried this and it worked for the first "sleep/wake" with the watch. But the 2nd time it did not. So I followed the above steps again. I noticed there was a 5th AutoUnlock (step 7) with a "piggy" suffix. Deleted this , too. Also, in System, Privacy "Disable automatic login" was checked (what does this do?). I unchecked it and checked "Use your Apple Watch...". Put Mac to sleep, pressed space bar, Mac opened using watch. Fingers crossed for the future.

For anyone like me that was desperate and went through this entire thread and followed everyone's suggestions without any luck, do everything listed in realstuarthobbs post. Then WAIT. I spent a few hours following everyone's suggestions to no avail. Finally, I decided to give up. I came back to my computer the next day and everything suddenly worked.

Tried everything on this thread including the toggle of the keychain & no luck.

Does Keychain have to be enabled on your iPhone as well as you Mac?

Keychain isn't something I've bothered with before.

Enabled Keychain on both Mac / iPhone, tried all the steps including the Keychain toggle + reboot but still no success.

Only thing i haven't done is unpair my watch & start from scratch but really can't be bothered to do that.

It's doing my head in now so think I'll give up & wait for a software update fix.

I kept trying, including turning off iCloud Keychain sharing.

It was not working for me.

Then I read a reply in a thread somewhere that the person left the Mac and Apple Watch sit over night, and the next day, they were able to enable unlock the Mac with Apple Watch.

So I tried the same thing. I did have to try twice to enable the Security option, but it seems to have worked today.

I do not know if it was just aging like fine wine (or allowing iCloud to stabilize all the keychains on all my devices, or other), or if I magically did the right thing. But it works on 2 Macs now.

I have exactly the same problem, and have attempted ALL of the above fixes. This only happened (to my knowledge) after the update. I have tried to re-pair the watch, deleted the keychains required, toggled keychain on and off, no matter what I do this just keeps on failing. I have logged out of iCloud, on all devices and logged back in. You name it, short of throwing my MacBook in a tub of sulphuric acid, I am all out of options. Has anyone managed to get a solid response from Apple yet regarding this problem, as it seems to be a growing number of people struggling with the same thing. Is there possibly a keychain virus that has wangled its way in? I would love some assistance. Apple Watch 3 and MacBook Pro. All running latest softwares.

Any help would be great, many thanks.

G

It’s not a virus. It’s basically a disconnect between the Apple Watch encryption keys and the computer. It took me a while to get it to work. Basically I could see when it wasn’t working. Those files ltk.plist and the pairing plist were empty. Also, my Keychain did not have the Apple Watch Auto Unlock entry. When it was working, the auto unlocks populated, the plist entries had stuff in them, etc.

Following! Same issue here with a 2018 Mac Mini I just got a month or two ago. Hadn't tried the watch unlock feature till the last couple of days and none of the suggestions here have helped either. I even moved the Mini around so it was farther away from some USB 3.0 hubs because I had read something about interference with wifi signals but still, no go.

mark__t was on it! Good Job! I did have to do a bit more to get my brand new MacBook and new MacMininto work. I followed your directions but it didn't work until I disabled Keychain in iCloud settings on both computers, re-booted each of them, then re-enabled Keychain in iCloud.

I think you hit the nail on the head! I found Auto Login from several devices from YEARS ago in my Keychain. When I followed mark__t's advice, there were like 30 of them in my Keychain. Cleaning them out, rebooting without iCloud Keychain, and finally re-enabling iCloud Keychain allowed it to work the way it should. Thanks mark__t.... You're awesome!

starfrenzy wrote:

Yesterday I upgraded from the iPhone 8 Plus to the iPhone 12 Pro and now my watch won't unlock my MacBook. I get the same error message as this subject line.

Did you try the "Solved" reply that involves deleting things via "Keychain Access"?

that has worked for a lot of users.

If you have multiple devices sharing your Keychain via iCloud, it may take awhile before all the devices exchange messages and settle down so that your Apple Watch will reliably unlock your Mac. I succeeded the next day in able to set the Security option and have it stick (on the 2nd try that is) and work from then forward.