Face ID is Apple’s latest security feature that debuted with the iPhone X, and with Apple removing Touch ID from the iPhone X, it means that for the most part, it has become the main method of authenticating users. Unfortunately it seems that with the iOS 11.2 update, Face ID appears to have stopped working for some users.
iOS 11.2 was released earlier today and with the update, it brought about support for Apple Pay Cash and also faster wireless charging in addition to a bug that caused soft reboots on the 2nd of December. However some users are claiming with the update, Face ID has stopped working for them, although for some, turning the device on and off managed to get it up and running again.
To restart your iPhone X, Apple has listed the steps on its website, where all users have to do is press the Side button and either volume button until the slider appears, then drag it to turn the iPhone X off. Once the device has been turned off, press the side button again until the Apple logo appears and you should be good to go.
This fix seems to work for most users but in the event it does not, we suppose you could try to factory reset your phone, or worst come to worst, take it in to the Apple Store for them to take a look at the device for you.