Have you noticed your iPhone - or iPad or iPod touch - crashing today? You're not alone. And yes, it's another weird, random iOS bug that's to blame.
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Forum user Eccanz describes the problem well over on the Apple support forum:
Woke up this morning and my iPhone started to restart by itself. I can use it to make calls without issue, but apps and text messages have to be quick Before it quickly restarts to a black screen and the spinning star thing before it is fine for another minute.
In the run-up to the crash, handsets are reported to heat up noticeably.
The problem it seems is a bug in iOS 11 that causes processor usage to spike to 100 percent when apps generate a notification. This causes the device to heat up, which, in turn, causes a reset.
Annoying. Fortunately, there's a fix. And it comes in the form of iOS 11.2. And Apple seems to have already documented this on its support site:
If your iPhone, iPad, or iPod touch unexpectedly restarts
If your device with iOS 11 unexpectedly restarts repeatedly on or after December 2, 2017, learn what to do.
Use these steps to turn off notifications for all the apps on your device, then update your device to iOS 11.2:
1. Tap Settings > Notifications.
2. Tap an app, then turn off Allow Notifications. Repeat this step for each app.
3. Update your device to iOS 11.2.
4. After updating, tap Settings > Notifications and turn Allow Notifications on again for each app.
If you're unable to update or still have issues after the update, contact Apple Support.
Published Date: Dec 2, 2017
If you're interested in knowing more about this problem, this post on Reddit is a good read. If you just want the problem fixed, follow the steps outlined above.