Your Mac was unable to communicate with your Apple Watch.

@TiggerGTO yes I had to re-enable ApplePay as well, but only had to confirm the security code of the cards I had on my phone and watch. Sorry to hear of your experience. I went through your solution several times with various permutations of rebooting in between steps, but never got to where the Mac would be unlocked by my watch. Looks like it did work for most of the people who have given feedback to the two threads I have seen on here for it though, and that is awesome. My follow-up reply was meant as something to try for those whom your excellent step-by-step instructions didn't work for.

What is really sad though is that a) this fails in the first place, and b) no better hints of the actual problem is in the system logs nor in the dialogue box. Takes away from the impression of robustness of the Apple products...

Unable to get two watches to Auto-Unlock

I own a series 5 aluminum and a series 6 stainless watch. After unpairing and re-pairing the watches to get my fitness / activity / health tracking corrected, I am now faced with this issue of auto-unlocking my MacBook Pro.

I have done everything in this thread (following Mark's deletion of keychain files, turning keychain off/on in iCloud, restarting all devices, etc) and can only get one watch to be set for auto unlock. In the past I had two watches that worked perfectly (Series 0 and Series 5). I removed the Series 0 from my account when I purchased the new Series 6.

I can only get one or the other to remain set for the auto-unlock. I have spent literally hours trying to get both to work. Anybody else in this situation and have you found a solution? Thanks!

TiggerGTO-

Thanks so much for your persistence and followup. Much appreciated for the link to mark__t 's fix. As i posted previously, I was able to get that solution to work for one watch but when I went to add my 2nd watch, it wouldn't connect. After mulitple attempts to try to get both watches to work, I walked away assuming one is better than none. Several hours later, I tried to get my 2nd watch connected after wearing it for awhile. Amazingly, it finally communicated and I now have both watches working. My guess is there is a delay in setting up handshaking between the watch and my Macbook Pro. When I switch watches, sometimes I get "unlocking with Apple Watch" and then it prompts me for a TouchID. Seconds later, it'll work.

Hopefully Apple engineering will figure out this communication issue. In the mean time, for those that use two watches, I suggest following the above procedures, set up the first watch for auto unlock, put it away, put on your 2nd watch and let it be paired to your iphone for an hour or so. Then try setting up auto unlock for your 2nd watch. Finally worked for me!

Apple has released a new update for the watch today; along with the instructions that Mark_t provided it worked, as initially didn’t like it. But after a reboot - the MacBook offered to link up the watch and booyah, it’s connected!

It worked OK after I updated my watch with watchOS 7.0.2 - But..........after shutting down my iMac (Catalina 10.15.7) and restarting it NO LONGER WORKS. Blast!!! I hope this will get sorted when Big Sur comes out?

This worked for me, I had to restart the MacBook after the last step and then going back to System Preferences, turning on the feature and having it fail once, it worked the second time almost immediately.

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.

iamtmo wrote:

I have tried all the "Solved" process and rebooted all devices and Mac still doesn't see the Watch 4. All are running Latest Dev Betas. It worked before the Big Sur beta update 11.0.1 Beta (20B5012d) even with latest iOS beta updates so that tells me it's the MAC OS update not the iOS and Watch updates.

We cannot discuss beta software in these forums (see the terms of service for the forum, and for your beta software aggrement). When you agreed to the beta software you were also given a way to report beta problems. Suggest you take advantage of that method.

When I searched my keychain for `watch`, I found out it had two entries for watch passwords (I've been resetting my watch a while back because of battery issues). I removed the two entries and boom, it was enabled. I tried everything described above, logging in and out of iCloud, but this was the only thing working for me.

RedboneRambler wrote:

So, this works to a small extent, but whenever I try it, it will only allow my watch to unlock the computer once. After this, it disables the feature, and I have to go through the entire process again.

I found AFTER doing the steps in the current thread, that I needed to follow the steps in this reply over in this thread

https://discussions.apple.com/thread/251826134?answerId=253504359022#253504359022

I also found that it took awhile for the iCloud Keychain records to propagate and merge on all the systems. More so when you have multiple devices sharing the keychain (I have 4 Macs, the iPhone, and the Apple Watch). I followed both of the above threads, but it was not reliably working until the next day, when I tried again. And I did have to click the enable check box twice the next day, but then it stuck.

SUCCESS! But a strange journey. I followed all the fixes and I came up empty. I restarted my iMac. I reset my iPhone and watch to factory settings nothing. I went through the check list a bunch of times. Turning bluetooth on and then off. Same with Wifi. Reboot, Reboot, Reboot and nothing.

The last thing I did was this. And I did it in this order. First, I unpaired my watch from my iPhone. THEN after unpairing, I RESET my watch and erased it (keeping my wireless plan, it asked). Then I paired it again with my iPhone.

Then I went to System Preferences, Security and Privacy and checked the same box "Use your Apple Watch to unlock....". The little spinning wheel started the usual spin BUT THIS TIME it kept spinning and spinning and spinning for what seemed like 4 times the normal. THEN SUCCESS..It linked. Seriously, I tried everything about 6 times. BUT This actually worked.

FINALLY FINALLY FINALLY This worked! It took MANY, many attempts to finally get this to work! I restarted at different stages after deleting the files and MISSED a couple times to delete the items under "autounlock" AND "auto unlock" in keychain...then, after one of the restarts, it now works perfectly like there was no issue! THANK YOU!!