Users Report Some iPhones Won’t Charge if Plugged in While Asleep

A shiny new smartphone can do all manner of cool things like snap high-quality photos, recognize your face, and run an almost uncountable number of apps. You would also expect it to do some basic things like charge when you plug it in. That seems to be a challenge for Apple’s latest iPhones. Users are now reporting that the phones won’t charge if you plug them in while the screen is off.

According to reports, not all devices suffer from this issue. Those that do will simply refuse to draw power from the cable. If you wake the screen while the Lightning cable is plugged in, it will immediately begin charging normally whether the screen is on or off. This could be quite aggravating if you plug the phone in when it’s nearly dead in the evening and awake to find a completely empty battery. The fact that not all phones behave in this way suggests this is a bug and not merely an ill-advised feature decision by Apple.

The initial report claimed it was only Apple’s latest iPhone XS and XR devices, but owners of previous-gen iPhones and iPads have since come forward to say they are all affected. The thread tying all of them together is iOS 12. In addition, the big seems only to affect wired charging. When setting an iPhone on a wireless charger, the device will begin charging regardless of whether it was awake at the time.

The apparent connection to the wired connection has led some to suspect this bug has some connection to USB Restricted Mode. Apple began using this feature over the summer on iOS 11 builds (starting in 11.4.1) to block law enforcement snooping on locked phones. Expensive pieces of hardware like the GrayKey can crack iPhone security using private exploits injected over USB. Restricted Mode prevents new USB devices from connecting after the phone has been asleep for several minutes. It’s not a perfect solution, but it helps. It’s possible iOS 12 has a big in Restricted Mode that is also affecting charging cables. To be clear, this is not the intended behavior of USB Restricted Mode.

Apple has yet to respond to the claims. If there is a bug causing charging problems in iOS 12, the company should be able to rectify matters with a quick software update. In the meantime, make sure you wake up your iPhone screen after plugging it in just to be safe.