iPhone 16 Pro on iOS 18.1, unexpectedly shutting down

While it is called an iPhone, it is actually a very powerful pocket-sized computer that can incidentally make phone calls. And like all computers, it will crash occasionally, and that’s what happened. To minimize the probability of that happening it may pay to restart it occasionally→Restart your iPhone - Apple Support

If it happens repeatedly contact Apple support so they can run diagnostics.

Have you installed any 3rd party “helper” apps, such as an antivirus, a memory management app, an app that purports to speed up the phone, or a VPN package, or anything related? Have you jailbroken the phone?

MLHV1 wrote:

I'm also experiencing this same kind of issue on my iPhone 13 Pro Max. Several restarts daily and sometimes it reads my battery as 10% and then if I restart it myself it jumps to the correct percentage (most recently 10% to 80%).

On iOS 18.1 and this experience is just terrible

What model iPhone?

How long has it been since the iPhone was new?

Go to Settings/Battery/Battery Health and report what it says about peak performance and Maximum Capacity.

Well, if the problem was 18.1 there would be many thousands of posts about it. It is a failing battery, possibly coincident with the update; contact Apple Support and they can check the battery with a diagnostic. But 3 years is far more life than most iPhone users get out of their battery.

And I really don’t care whether you take my advice or not.

I suggest you run a diagnostics, I have ran a diagnostics on my iPhone for whatever it’s worth and every time it has came back perfectly fine for hardware issues, this is probably just a bug that we have on our phones that should be addressed fairly soon with a new version of IOS for improvements. (I guess some people where saying that it already fixed the problem, but sadly for us at least this didn’t help)

To run hardware diagnostics: How to put your iPhone in diagnostics mode - Apple Support

I'm also experiencing this same kind of issue on my iPhone 13 Pro Max. Several restarts daily and sometimes it reads my battery as 10% and then if I restart it myself it jumps to the correct percentage (most recently 10% to 80%).

On iOS 18.1 and this experience is just terrible

Are you still having issue?- I have a iPhone 16 pro that reboots on its own. Like you said I did not seem to notice it do this on IOS 18.0.1, I first noticed it on IOS 18.1 , however naturally as I am sure you probs know IOS 18.1 was supposed to fix this issue and I think it only fixed the issue for certain devices clearly, and clearly not all of the iPhone 16s like it said it would. I erased all content and settings on my iPhone set the device up as new and a couple of days later the issue persisted again, and then IOS 18.1.1 came out and a couple of hours after the install I have still been experiencing the issue, my device passes diagnostics every time indicating no hardware failure though.

My iPhone 16 Pro with IOS 18.1 restarts 2-3 times every hour, this problem started 2 days ago and is very frustrating, every time it restarts is running slow it doesn't connect to my WiFi network and CarPlay stops working I have to shut down manually and then everything stars working normally until it restarts again by it self.

Same thing. I have a 3 month old iPhone 16 Pro. Have had zero issues, upgraded to 18.1.1 this morning and for the past 5 hours it’s been rebooting at least twice or more an hour. It’s really frustrating.

No, never jailbroken the phone, no one of the apps, I have the phone for 1 month and never had this issue until 2 days ago

Same with the reboots.

Max Capacity is 84%

Peak Performance Capability

iPhone is 3 years old.

This is due to iOS 18.1.

This is not a phone issue. Previously on 18.0.1 (last week) had ZERO issues

Sounds good.

Thank you for the advice. I'll try and get my battery replaced