Don’t click on any .mp4 files anyone sends you. Users recently discovered a strange 3-second video that is freezing iPhones.
By Eric Limer
Watching videos on your iPhone is typically a pretty harmless experience, but a new, strange video going around is an exception to the rule. As Redditors discovered, one unusual three-second clip will actually lock up virtually any iPhone, requiring owners to hard reset their device before they can use it again.
The video only seems to take effect when the a particular .mp4 video file is viewed in the iPhone’s native media player. The clip, shown playing on an iPhone above, plays normally including sound and appears to be a normal video at first blush. However, those who play it will find that over the course of the next 30 seconds or so, their device will slow to a crawl before freezing completely.
Here’s YouTuber EverythingApplePro illustrating the effects on a number of different iPhones running a number of different versions of iOS:
The exact cause is still unclear, but it appears that something in this video is corrupted, and when iOS tries to decode it, the corruption sends it spiraling into an infinitely repeating loop. At first this has no noticeable effect, but as the loop continues to copy itself, it starts to tax the processing power of the phone, first making it sluggish and then ultimately bringing it to a complete halt.
Fortunately, there seem to be no lasting effects once you reboot, but leaving the phone on in this frozen state could be detrimental just in that it tends to make phones hot, and that’s not good for a smartphone battery.
This isn’t the first time a strange bug like this has effected iPhones. Last year a strange text message was discovered to crash any iPhone it was sent to. Apple released a firmware update fixing the issue within a couple of days, and it’s likely a new version of iOS will be coming down the pike soon to fix this issue as well. In the meantime, don’t click any .mp4 files that are texted your way by prankster friends. If you do, a hard reset is Lock button plus Volume Down on an iPhone 7, or Home button plus Lock button on anything earlier. Be careful out there.
This article was originally written for and published by Popular Mechanics USA.