What triggers the reboot?
The problem does not appear to happen every time Face ID fails.
Reports indicate it can occur when users try to authenticate inside protected apps, not just when unlocking the iPhone from its lock screen.
That could include Apple’s Passwords app, private Safari tabs and other apps that users have configured to require Face ID.
In testing by 9to5Mac, covering the face to deliberately cause authentication to fail, then attempting Face ID again, caused an affected phone to become unresponsive and restart.
Diagnostic information on the device subsequently showed a system panic log.
Users should not deliberately attempt to reproduce the crash on their own phones.
What’s different about Face ID on iPhone 18 Pro?
Apple redesigned the Face ID system on the iPhone 18 Pro and Pro Max.
The system’s infrared camera has moved beneath the display near the clock in the status bar, helping Apple reduce the visible size of the Dynamic Island.
There is currently no evidence establishing that the hardware redesign itself caused the reboot problem.
Apple’s confirmation of an upcoming software update indicates the company can address the reported issue through iOS.
Not every iPhone 18 Pro owner is experiencing the bug, and its overall prevalence remains unclear.
For affected owners, the important development is that a fix is now expected shortly rather than requiring a hardware change.