Following the update to iOS 11.2, some users with iPhone X have complained about a problem with Face ID.
This firmware was released in a rush because in the previous version there was a bug, called by all “Bug of 2 December”, which caused endless respring every 30 seconds starting from 2 December morning.
The new problem concerns the Face ID. In particular, some people appeared with a popup saying: “Impossible to activate Face ID on this iPhone”.
A problem that, from the message, seems to be quite serious as it immediately goes to think of a damage to the TrueDepth camera. In reality, the question is very simple to solve: just restart the iPhone.
Probably a new version of the firmware will still be released if this problem is widespread.