Can't unlock your Mac with your Apple Watch? Here's how to fix it!

Auto Unlock
Auto Unlock (Image credit: Rene Ritchie / iMore)

When the Apple Watch's Auto Unlock works, it's magical. You open or approach your Mac while wearing your Apple Watch and, instead of having to type in your — hopefully long, strong — password, it just logs you in. No fuss. No muss.

But when it's not working, you might feel anger, frustration, blame, recriminations, along with having to type in that — hopefully long, strong — password. Not so much fun.

So what can you do when Auto Unlock doesn't work? Here's an in-depth guide to help you out.

Some basic Auto Unlock troubleshooting

If you can't enable Auto Unlock (or it was working, but stopped), here are a few of more obvious problems we've run across:

  • Your Mac is not compatible: Remember, to use Auto Unlock, you must have a 2013 Mac or newer.
  • Your software isn't compatible: If you own an Apple Watch Series 0, 1, or 2, you'll need watchOS 3 or later and macOS Sierra or later to use Auto Unlock; the Apple Watch Series 3 requires watchOS 4 and macOS High Sierra or later.
  • You don't have two-factor authentication enabled for iCloud: Either you never enabled two-factor authentication, or you still have Apple's older two-step verification procedure enabled instead.
  • Your Mac and Apple Watch are signed into different iCloud accounts: Make sure your devices are both signed in with the same Apple ID.
  • Your Apple Watch or Mac don't have a passcode enabled: Both devices should have a default passcode enabled to use Auto Unlock — otherwise, what are you unlocking?

You can also check your setup process and make sure everything's still working there:

These quick fixes fail to address your issue? Check out our more in-depth troubleshooting options below.

Is Automatic Login enabled?

If so, you should disable it.

  1. Click on the Apple icon in the upper left corner of your screen.
  2. Select System Preferences from the drop-down menu.

Opening System Preferences on Mac

Opening System Preferences on Mac
  1. Click on Users & Groups.
  2. Click the lock to make changes.
  3. Enter your system administrator password.
  4. Click on Login Options.
  5. Select Off from the Automatic login menu.

Disabling Automatic login on Mac

Is your Apple Watch paired correctly?

This has happened to iMore staffers before: Editor Lory Gil had forgotten to pair her existing Apple Watch with her new iPhone, which momentarily broke Auto Unlock.

How to pair your Apple Watch to a new iPhone

Reset the radios

Auto unlock requires Bluetooth 4.2 and Wi-Fi to be up and running on both your Apple Watch and Mac in order to work. If one or both radios have been turned off on one or both devices, or somehow stopped responding, Auto Unlock will likewise stop working. Cycling them can sometimes jump start everything back into action.

On your Apple Watch:

  1. Swipe up from the watch face to bring up control center.
  2. Tap the Airplane Mode button to turn all radios off. (It'll turn yellow when they're off.)
  3. Tap the Airplane Mode button to turn all the radios back on. (It'll go back to black and gray when they're on.)

Apple Watch airplane mode (Image credit: iMore)

On your Mac:

  1. Click on the Bluetooth icon in the menubar.
  2. Click on Turn Bluetooth Off.
  3. Click on the Bluetooth icon in the menubar again.
  4. Click on Turn Bluetooth On.

  1. Click on the Wi-Fi icon in the menubar.
  2. Click on Turn Wi-Fi Off.
  3. Click on the Wi-Fi icon in the menubar again.
  4. Click on Turn Wi-Fi On.

Mac Wi-Fi (Image credit: iMore)

Once you're done, try auto-unlock again. If it works, great. If not, keep reading.

Reboot everything

The next thing to try is a hard reset. Make all the "reboot Windows" jokes you want but it's a cliche for a reason!

On your Apple Watch:

  1. Press an hold the Digital Crown and Side button at the same time.
  2. Keep holding them down until you see the Apple logo.

On your Mac:

  1. Click on the Apple button on the menubar.
  2. Click on Restart...

Once you've rebooted, auto-unlock will be temporarily disabled. Enter your password to re-enable it. Then let your Mac sleep and try auto-unlock again.

Check for updates

Apple's Bluetooth and Wi-Fi stacks—the set of software that controls the radios—aren't without occasional quirks. Sometimes, new versions of watchOS or macOS introduce compatibility problems; other times, they fix them. If you're having Bluetooth or Wi-Fi connectivity problems, you're better off updating than not. If it's already broken, the update is your chance for a fix.

On your iPhone:

  1. Launch the Watch app on your iPhone.
  2. Tap on the My Watch tab at the bottom.
  3. Tap on General.
  4. Tap on Software Update.
  5. If there's an update available, tap to install it.

On your Mac:

  1. Launch the Mac App Store.
  2. Click on the Updates tab, top left.
  3. If there's a macOS software update available, click to install it.

Once you're done updating, try to use auto-unlock again — after you've logged in follow with a reboot to re-enable it! If it works, awesome. If not, there's even more to try!

Re-pair your Apple Watch

Re-pairing your Apple Watch is a huge pain, but if something has gone wrong with the connection between your iPhone and Apple Watch, secure information won't be transmitted properly, and that will stop auto-unlock dead.

  1. Launch the Watch app on your iPhone.
  2. Tap on the My Watch tab at the bottom.
  3. Tap on (Name)'s Apple Watch at the top.
  4. Tap on the Info button on the right. (Looks like an i.)
  5. Tap on Unpair Apple Watch.

Apple Watch unpair (Image credit: iMore)

Once your Apple Watch has been unpaired, repeat the pairing process, restoring from your most recent backup. You'll have to re-enable Auto Unlock in your Mac's System Preferences again, but once that's done, auto-unlock should be back up and running. If not, you have one option left...

Contact Apple

Sometimes a problem really is a problem. Like any electronics, Bluetooth and Wi-Fi radios and the various connections to them can have problems. If you have AppleCare+, don't walk, run to your local Apple Store to get it looked at.

Other questions?

Let us know below.

Updated December 2019: Updated to reflect macOS Catalina and watchOS 6.

Bryan M Wolfe
Staff Writer

Bryan M. Wolfe has written about technology for over a decade on various websites, including TechRadar, AppAdvice, and many more. Before this, he worked in the technology field across different industries, including healthcare and education. He’s currently iMore’s lead on all things Mac and macOS, although he also loves covering iPhone, iPad, and Apple Watch. Bryan enjoys watching his favorite sports teams, traveling, and driving around his teenage daughter to her latest stage show, audition, or school event in his spare time. He also keeps busy walking his black and white cocker spaniel, Izzy, and trying new coffees and liquid grapes.