A dodgy post has been doing the Internet rounds this past week, encouraging people to set the date on their iPhone back to 1970 for "wild" results. But what the date change actually triggers is a newly discovered bug that promptly 'bricks' your phone, effectively turning it into a fancy-looking, inert paperweight.
The bug presents itself if you set the internal date back to 1 January 1970 in the iPhone's Date & Time settings. And it's not a cute trick that you should try for yourself – winding the clock back that far and rebooting the device is said to render the device completely unusable. Don't give in to curiosity on this one, folks! Just leave it alone.
While it appears this unfortunate glitch may have been discoverable for some time, awareness of the bug and the problems it causes has only recently blown up on the Internet after a deliberately misleading image started circulating on web sites and social media.
The image, seen below, which reportedly first appeared on 4chan, emulates the appearance of Apple's promotional material and urges people to change the date on their devices and then reboot, promising a "wild ride" for those who are game.
The implication is they'll discover a hidden Easter Egg in the form of a retro '70s-style Apple logo from the company's past. Unfortunately, this doesn't actually happen. What does happen is your expensive iPhone becomes an expensive non-phone.
According to reports, the rebooted device will be inoperable and cannot be restored via iTunes backups, and even 'Genius' staff at Apple Stores are unable to fix the problem, meaning you could have to get an entirely new phone.
It's also not limited just to iPhones, and can affect iPads and iPod touches running iOS 8 or iOS 9. However, only newer iOS devices running on 64-bit processors appear to be affected by the glitch, including the iPhone 5s or newer, iPad Air or newer, iPad mini 2 or newer, or sixth-generation iPod touch. (Even if you've got an older device, however, we wouldn't recommend playing with fire!)
So why does this crazy bug brick your iPhone in the first place? At time of writing Apple hasn't confirmed anything, but it's being speculated that winding the clock back to 1 January 1970 – which just happens to be a fundamental date in the way that Unix-based computer systems process time – is creating what could be an 'integer underflow'.
Called the Unix epoch, that date is effectively Day Zero as far as Unix computers are concerned, the point from which all subsequent time is counted and calculated.
And by setting the date at this time, at least according to speculation online (and seen in the video below), it's possible the software in the phone is trying to calculate other retrospective things – such as battery life estimates, perhaps – in relation to times or dates that happened before Day Zero.
This, as far as the phone might be concerned, is impossible. In any case, the resulting attempts at reconciling the date end up bricking the iPhone entirely.
In the absence of an explanation from Apple – which will likely issue a software patch at some point to address the issue – nobody knows for sure if this hypothesis is exactly what's causing this problem. But for most of us, as Brian Barrett at Wired puts it, fully understanding the root of the glitch isn't really as valuable as simply knowing what not to do here.
"The why and who are less important," he writes, "than the what, and the what is: don't set your phone's calendar back. Live in the present. It'll save you a lot of future headaches."