Big Sur - Unlocking with Apple Watch

I had the same issue with Apple Watch 6 (watchOS 7.1) and MacBook Pro 13 early 2015 (Big Sur). So I repaired it with some steps:

1) I disabled Keychain synchronisation on MacBook (Settings/iCloud/Keychain)

2) I made steps in this thread https://discussions.apple.com/thread/251803595?answerId=253458029022#253458029022

• • Open "Keychain Access"
  • In "View", enable "Show Invisible Items"
  • Search for "Auto Unlock"
  • You should see a whole bunch of application passwords for "Auto Unlock: XXXX's ..."
  • Select all records and delete (this will reset/disable auto unlock on other Macs if you use multiple Macs)
  • Whilst still in "Keychain Access", search for "AutoUnlock" (no space)
  • There should be 4 entries for "tlk" "tlk-nonsync" "classA" "classC"
  • Select 4 records and delete (don't worry if they re-appear, the system repairs this automatically)
  • Open "Finder" and navigate to "~/Library/Sharing/AutoUnlock"
  • There should be two files "ltk.plist" and "pairing-records.plist"
  • Delete both files

3) Disconnected Watch from iPhone

4) Connected back Watch to iPhone (set it from backup)

5) Restarted MacBook

6) Turned on Keychain in iCloud settings

7) Enabled Auto Unlock for Watch in System Prefs

Update to watchOS 7.1, as it has a fix for unlocking Macs

If that does not work, it should, but if it does not work, then read the following threads

Check out this thread on fixing Apple Watch unlocking Mac

https://discussions.apple.com/thread/251803595?answerId=253458029022#253458029022

Then follow with this thread

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

And

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.

And this thread says they also had to toggle the Apple Watch -> Settings -> Siri -> Listen for "Hey Siri" option off then on

https://discussions.apple.com/thread/251803595?answerId=253782332022#253782332022

Hints (you will understand when you read the first and second threads):

Applications -> Utilities -> Keychain Access

Finder -> Go menu -> ~/Library/Sharing/AutoUnlock

System Preferences -> iCloud -> Keychain

After installing Big Sur 11.2 update today, I can finally check the 'Use your Apple Watch to unlock apps and your Mac' option in System Preferences > Security & Privacy again! That was a long wait, but this option work again thankfully. Huge time saver!!!

For me the helpful comment didn't solve the issue.

Instead, what did solve the issue for me was:

1. Sign out from iCloud on your Mac
2. Restart Mac
3. Sign in to iCloud
4. Enable unlock with watch.

This solved the issue for me.

Only had to do these steps and then checked the box to turn on the settings and it works!! Hooray. I haven’t been able to unlock my Mac with my watch since upgrading to the 16inch MacBook 6 months ago!!!

• Open "Keychain Access"
• In "View", enable "Show Invisible Items"
• Search for "Auto Unlock"
• You should see a whole bunch of application passwords for "Auto Unlock: XXXX's ..."
• Select all records and delete (this will reset/disable auto unlock on other Macs if you use multiple Macs)
• Whilst still in "Keychain Access", search for "AutoUnlock" (no space)
• There should be 4 entries for "tlk" "tlk-nonsync" "classA" "classC"
• Select 4 records and delete (don't worry if they re-appear, the system repairs this automatically)

I have a Series 4 with watchOS 7.1 and MBP 13 2018 (BigSur 11.0.1). These steps worked for me. A few minor details/differences:

1. I was unable to access the ~/Library/Shared folder to delete the plist files. Tried via Finder or attempting to sudo in. I skipped this step and everything seemed to come out OK.
2. Took me a minute to understand what was meant in step 3 - Disconnected Watch from iPhone. I believe you meant go into the iWatch app on your phone. Select General->Reset->Erase Apple Watch Content and Settings. Which is what I did. This basically resets it to factory.
3. Pair your Watch with your phone again. The process is like it was out of the box new, but you'll have a restore from backup option. Which I also did. Make sure your battery levels are up. Takes 15-20 mins to restore from backup.
4. When you turn on keychain sync again the checkbox will be grey. Wait until it turns blue to confirm sync.
5. If you use a VPN, disable it before trying to turn on Auto Unlock for Watch under System Pref->Security&Privacy->General. I kept getting errors that my Mac couldn't communicate with my watch until I turned off VPN. Worked immediately once VPN was off.
6. Once paired I turned on my VPN and it looks like everything is good to go and I can unlock successfully now.

I've had intermittent success with watch unlock for over a year now. It started working reliably with the watch 7.1 update and then Big Sur promptly broke it again. Fingers crossed things are stable from here!

I finally got it to work, but only after doing a reset on the watch, which is basically erasing all its content and settings, unpairing it from the from the phone, then pairing it agains and restoring it from the backup on the phone.

I can't wait to see what other surprises Big Sur has for me.

Thanks a lot. That procede worked for me too

its much easier and faster than one might think. I did a restart of the Mac and checked/unchecked „unlock with Apple Watch „ 2 or 3 times.

important: before you check the box , you have to unlock your iPhone ! Otherwise you get an error that the watch could not be connected.

than I had to wait some minutes for the watch to work.

Quite easy or me:

• go to settings > security&privacy
• check for 'use apple watch to unlock'
• apple watch passcode should be enabled

Big Sur 11.1 on a MacBook Pro and Series 4 watchOS 7.2. After the updates, did restarts on both. No luck. Restarted both MacBook and watch a few hours later and now watch unlocks MacBook.

I have the same question

This solved my problem. It's rather laborious, took me almost half an hour, not all watch settings were restored from backup, but it appears the unlock is working again. I hope I'm out of the woods because this Watch Unlock thing has been brittle since the beginning.

Besides the horrendously slow boot - I have this problem as well with my Series 3. I'm really regretting this OS upgrade.

It doesn't matter whether the settings are unlocked on the iMac or not, or whether the phone is unlocked or not. I'm using an iPhone12 Pro Max - and backing it up to my Mac, so the computer knows it exists and is trusted.

So, I updated my MacBook Pro 16in. 2019, my iPhone 10R and my Apple Watch Series 5 today to the latest versions of OS and iOS. After futzing around a bit, I got my Apple Watch to unlock the MBPro. That worked when I put the computer to sleep and when I closed and opened the cover. (basically the same thing)

I tried going to the Lock Screen but then I had to use Touch ID as the Watch didn't come up as an option. It still worked when I put the computer to sleep and woke it up again. I thought, GREAT! It's working again!

Not so fast…

After logging in a second user on the MBPro my Watch stopped unlocking it again, the same exact problem as before updating to Big Sur. So, after all the months of working withs Apple Advisors and all the updates and new operating systems, the problem STILL exists.

Once I finally got it working, it started unlocking the computer when I was actually in the next room. I'm turning it off. It's one of those little conveniences that sounds good, but turns out to be more trouble than it's worth. Especially, since Apple apparently has no interest in fixing it.