Apple’s new flagship models, the iPhone 18 Pro and iPhone 18 Pro Max, recently released to users, have come to the forefront with an annoying hardware/software bug shortly after the first shipments. Some users who purchased on day one report that the biometric security system Face ID freezes, locks up, and restarts the device in certain scenarios.

Face ID Locks Up and Phone Shuts Down

According to complaints shared on user forums and Reddit, the problem occurs especially when trying to unlock a locked application with Face ID. Immediately after the facial recognition process fails, the screen freezes completely, and the phone remains unresponsive for a while before automatically restarting and returning to the lock screen. It is not yet clear whether this problem affects all users or only certain production batches.

Main Problems Encountered by Users

Initial feedback indicates that the flaw is not limited to application locks. Other technical issues highlighted in the forums are listed as follows:

• Installation Error: Some users encounter the “Face ID Unavailable” warning directly during the first installation.
• Attention Detection Problem: It is stated that the sensors do not always accurately detect eye contact even when the “Attention Required for Face ID” option is enabled.
• Screen Protector Effect: It is said that matte or privacy-filtered screen protectors that do not fully adapt to the under-screen sensor design reduce the scanning quality.

Was it the Under-Screen Infrared Sensor Design that Caused This?

Apple hid the Face ID infrared camera under the upper left corner of the screen in the iPhone 18 Pro family, apparently to reduce the Dynamic Island area. It has not yet been officially announced whether this radical architectural change has led to an incompatibility in terms of optical transmittance and software calibration.

However, experts believe that the crashes and restart loops are more likely due to a software error in iOS 27 that manages the new sensor layer, rather than a hardware failure. Apple is expected to fix these instabilities with an upcoming iOS 27 interim update.