An unknown number of iPhone users have reported having problems with Face ID not working immediately after updating to iOS 16.
Face ID
It's unclear how many people are affected by the Face ID bug, nor whether only particular models of iPhone are affected. However, it is not a widespread issue.
In a Reddit thread first started two months ago, a growing number of users have reported that updating to iOS 16 has resulted in Face ID stopping working afterward. The thread's original poster shared an error message that said, "Face ID is not available, try setting up Face ID later."
It was posted in the iPhone X subreddit, although one person had trouble with Face ID on their iPhone 13 Pro Max. Someone else said they brought their iPhone into an Apple Store, where the technicians claimed it was a hardware error.
An Apple customer wrote in the company's community forums on October 27, saying that they updated to iOS 16.1 and found that Face ID no longer worked. Rebooting and resetting Face ID didn't seem to help.
In early October, MacRumors reported that the iOS 15.7.1 Release Candidate -- not the official release -- broke Face ID for some people.
Apple has a support page on steps to take if Face ID isn't working on an iPhone or iPad Pro. They include checking for updates or Face ID settings and ensuring that nothing is covering the front-facing camera.
However, this is a general support page, rather than one directly addressing this particular Face ID error. Apple has not issued any support documents about the issue, nor commented publicly on it.