Some iPhone 18 Pro and Pro Max owners say their phone freezes and reboots after Face ID fails. It shows up when Face ID is guarding a locked app, like the Passwords app or a private tab in Safari. It doesn't seem to happen at the lock screen. 9to5Mac reproduced the bug on a European iPhone 18 Pro, and it doesn't hit every phone. Face ID misses on the first try, you tap "Try Face ID Again" in the alert, and the screen stops responding to touch. A few seconds later the phone restarts to the lock screen.
The new Pros moved Face ID's infrared camera under the top-left corner of the display, which is how Apple shrank the Dynamic Island. Nobody has tied the bug to that change. Forum members on MacRumors describe other Face ID trouble on the same phones: a "Face ID is Not Available" message during setup, and a Require Attention setting that isn't always honored. One owner on Reddit says Apple support suggested a hardware swap. Benjamin Mayo, who reproduced the freeze, expects a software update to fix it instead. A separate iOS 27 bug can also reboot any iPhone model.