Make sure nothing is blocking your face or your camera. For Face ID to function properly, your eyes, nose, and mouth all need to be visible to the camera. If it isn’t your clothes obstructing the view, make sure your finger isn’t covering the lens. You might also try removing or adjusting your phone case in case it’s getting in the way.

Ensure you’re holding your iPhone correctly. While Face ID on iPad works regardless of which way you’re holding the tablet, it won’t work on iPhone unless the phone is in portrait (vertical) orientation. Face ID also only works within a certain range of your face, so try holding your phone closer or farther away.

Clean the camera lens. Dirt and oil can stop your iPhone camera from working, so a quick wipe-down with a microfiber cloth can solve the problem.

Restart your phone. If physical fixes don’t work, a software reset may work. Try turning your phone off, power it back up, and enter your passcode. Then, lock it and try opening it with Face ID again.

Check to see if Face ID is on. Go to Settings > Face ID & Passcode, and then make sure the switches for the features you’re trying to use Face ID with (for example, Phone Unlock) are set to the on/green position.

Turn off “Require Attention.” One option in Face ID prevents it from working unless you’re actually looking at the camera. If your device isn’t unlocking, it’s possible the camera isn’t properly registering your eyes. To deactivate this feature, open Face ID & Passcode, and then scroll down and turn the switch next to Require Attention for Face ID to off/white.

Set up an alternate appearance. While Face ID can recognize you despite minor changes in appearance, like if you gain or lose facial hair or start wearing glasses, it won’t go along with more drastic differences.

On the Face ID & Passcode screen, tap Set Up an Alternate Appearance to add more looks to your phone. This option won’t replace your original face; it’s more like adding extra fingerprints to Touch ID.

Check for an iOS update. Face ID may need an update to start working correctly. Go to Settings > General > Software Update to see if a new version of the operating system is available. Once your device has downloaded and installed it, unlock it with your passcode, lock it again, and then see if Face ID works.

Reset Face ID. The most drastic measure you can take is to completely reset Face ID and set it up from scratch. In the Settings app, tap Face ID & Passcodes, and then select Reset Face ID. You’ll go through the initial setup again, and then you can see if your phone unlocks without issue.

Contact Apple. If nothing else works, your iPhone may have some hardware or software issues that require more intensive attention. Head to Apple’s support page to enter your specific problem and start a service request.