Apple made its iPhone more secure, and it seems no one really noticed until law enforcement got locked out of the devices they previously had or were trying to crack.

Last week, 404 Media reported in connection with a new phenomenon that was occurring, which was driving law enforcement crazy. iPhones that were being stored for forensics were “mysteriously” rebooting, making it harder for LEOs to collect evidence from the devices.

Now a researcher at the Hasso Plattner Institute, Dr.-Ing. Jiska Classen appear to have solved the mystery. Apple has quietly rolled out a new feature in iOS 18.1 that reboots a user’s iPhone if it hasn’t been unlocked for a certain amount of time.

The Tweet may have been deleted

Reboot from inactivity now makes an iPhone more secure

The new feature causing police headaches is called “inactivity restart.” While it may stifle some police investigations, it’s generally good for most users.

The inactivity restart code basically brings an inactivity timer to users’ iPhones with iOS 18 and later installed. The timer clock starts after it is unlocked or when a user unlocks their iPhone for the first time since it was turned on.

After four days of a device being unused and locked, it resumes idle and restarts the iPhone. Rebooting puts your iPhone in a “Before First Unlock” state, which makes it much harder for third parties, such as bad actors or law enforcement, to gain access with forensic or cracking tools.

A cryptographer explained to 404 Media that the practical reason for this feature is to discourage thieves from stealing iPhones, jailbreaking the devices and then reselling them or using your private data for nefarious purposes. However, it seems that law enforcement officials are affected by the change and are now spreading the word to others in the field about how to deal with it.

Regardless, though, it’s good that Apple continues to make updates and changes to further protect the security and privacy of its users.