Recently, there has been an iPhone reboot mystery where some iPhones have rebooted without warning and – it was thought – caused nearby phones to follow suit. But now it seems something else was going on.
Apple iPhones are rebooted. What’s going on?
The report came from 404media and was picked up by Kate O’Flaherty here at Forbes. It described “iPhones mysteriously restarting themselves” when police in Detroit, Michigan discovered that iPhones held for forensic investigation were restarting without any human interaction.
Once an iPhone is rebooted, it’s harder to unlock than after it’s been unlocked. This is the difference between the Before First Unlock and After First Unlock (AFU) states. Until this phenomenon was discovered, simply keeping the iPhone on would make it more accessible to the police. The police seemed to think that these iPhones were sending instructions to other nearby iPhones that they too should be rebooted.
The report says, “The document says three iPhones running iOS 18.0, the latest major iteration of Apple’s operating system, were brought to the lab on October 3. The hypothesis of law enforcement officials is that “iPhone devices with iOS 18.0 were introduced into the laboratory, if the conditions were available, communicated with other iPhone devices that were turned on in the vault at AFU. This communication sent a signal to the devices to reboot after so much time has passed since the device was inactive or offline.”
While it’s nice to think that iPhones could talk to each other this way, to stop them from becoming lonely, maybe, maybe not. It’s true that devices can send information, such as Find My Data, but this is something different, not least because some of the iPhones were in Airplane mode and one inside a Faraday cage.
While the police have suggested that this is a security feature addition for iOS 18, a user at Mastodon explained things differently, saying, “Apple added a feature called ‘idle restart’ in iOS 18.1. This is implemented in keybagd and the AppleSEPKeyStore kernel extension. It doesn’t seem to have anything to do with the phone/wireless network condition. The keystore is used when you unlock the device. So if you don’t unlock your iPhone for a while… it will reboot!”
This makes a lot more sense, although I note that the police were specific that the iPhones they had had iOS 18, not 18.1.
Another user has a different answer, saying that there was an iPhone reboot bug in iOS 18, which was fixed in iOS 18.1. This reboot issue affected some iPhone 16 Pro and Pro Max users. The iPhone reboot with iOS 18 matches what the police said. Apple Insider thinks this is the most likely explanation, though it’s curious that multiple iPhones in a small sample all had the same reboot problem.
Apple hasn’t commented, but it seems to me that this might be something simpler than all that: just as you’ll find that a Mac that’s been left idle will require a password unlock after a certain amount of time in place to boot from fingerprint or Apple. Unlocking the watch, so it makes sense to me that Apple would want users to re-enter their passcode after a while. And a good way to do that would be to restart the phone.
Whatever the explanation for the iPhone reboot mystery, I think it’s safe to assume that while machines may one day take off, they aren’t talking to each other, making plans together, or laughing at us afterwards back. However.