Why can't I unlock my phone with my face?

If you've already set up Face Unlock but your phone won't unlock, check the following:

• Make sure the front camera is not covered by your protective case.
• Make sure you're on the lock screen and not on the Smart display when you're unlocking the phone with Face Unlock.
• Move to a well-lit location.
• Remove your sunglasses or other things that cover your eyes.
• Check if Face Unlock got disabled because you activated a device administrator app, such as Exchange ActiveSync® security policies after signing in to your Exchange ActiveSync mail account.
• For added protection, Face Unlock allows up to 5 unsuccessful attempts. If you exceed this, you'll be required to use one of the screen lock options—screen lock PIN, password, or pattern—to unlock your phone.
• If you haven't used Face Unlock to unlock your phone for the past 72 hours, you'll be required to use one of the screen lock options to unlock your phone.
• Face Unlock may not recognize you if you have slight facial changes, for instance, due to mustache growth, suntan, or surgery. Go to Settings > Face Unlock to register your face data again.