Your Mac was unable to communicate with your Apple Watch.

Hi Tigger

I am having the identical problem re battery whereby my series 5 would drain within 6 hours after a full charge, I spoke with support and after many different attempts to resolve I was told also to unpair and pair again, however, since turning all the functions back on i.e. always on and hand wash I still only get around 10 hours.

The inability to now not being able to open the mac with my watch is driving me nuts! I will keep an eye on your post to see if any solutions come forward, I am reluctant to reset the watch again so maybe hold out until Mac OS is updated.

Hey thanks for reaching out, I wish that I could say it did but unfortunately not, I followed the guidance to the letter and tried a few restarts without success.

i then tried deleting the files once again (as you noted they had replicated again) and restarted and nothing, although it did speed up the response of displaying the error message!

I further tried some of the other solutions in other threads with switching off hand off and back on but nothing

driving me nuts as I use my mbp a lot and it worked a treat before IOS14 and unpairing my series 5

thanks again

My headache came when I bought my new Apple Watch SE. Wiped my old watch and traded it in. Got the new one, which works great BTW, a huge upgrade. But no more functionality for Auto Unlock on either of my Macs, which both worked fine with the old watch. I've tried all of the listed steps, but don't see a library entry (~/Library/Sharing/AutoUnlock) on either Mac. One's a MBP 2013 the other a MBA 2020. 🤔

Absolutely I think that is my next best step, thank you for posting all you have it seems a few have managed to get it to work.

ironic that we pay all this money and then find ourselves trying to resolve software issues!

take care

Another big thank you!! Turned the mac off (not a restart) and just switched it on after replying to you earlier and it worked!!!! Fantastic to have it back, thank you for sharing your guide, as I said earlier I copied it to the letter and it has now worked so hopefully others do the same and shut down rather than restart which seems to have done it for me.

Thanks!

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

Something mysterious about this whole thing.

For two days I have followed all the proposed methods, especially the one to erase the auto unlocks from the keychain, on my macbook from 2017 and on my mac mini from 2018, without success, a thousand times.
Today I updated my 27-inch imac from 2012 and the unlock option with the apple watch was successful on the first try. Then it occurred to me to try it on my mac mini and surprisingly I also got it on the first try this time. And then  i tried on my macbook and GOT IT AGAIN on the very first time,  not so surprisingly now.
 I think that part of the proposed solution to erase auto unlocks and so,  is trying to activate the unlock on all computers within the same icloud, once updated. Maybe, the system need to check ALL computers included in the icloud everytime auto unlock is required. What do you think about?

Just to add a voice to the mix. I was following apple advice to fix issues with activity routes not showing up after ios14 and iwatch 7.0.1 upgrades. Apples fix involved unpair and reinstall from icloud. Once this as done, I have been unable to use apple watch to unlock my mac. I tried the fix above and this did not work.

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 have exactly the same issue after running first into battery problems and unpairing and re-pairing my watch. I went through this process of deleting everything, restarted my MacBook Pro running the latest OS10 update (10.15.7) and still get the "Your Mac was unable to communicate with your Apple Watch." message when trying to set up my series 4 watch. I guess I will just wait for a fix.

Thanks

I had a upgraded my S3 to new Watch SE, nothing worked, I was on call to Support for two hours trying different things, I even sent my watch back and had a replacement.

The solution posted by Mark worked for me.