I don't use iOS but I came across New iOS bug causes some devices to crash on Dec. 2, here's how to fix it If you are affected, it should help.

iOS 11.2, which is now available, fixes this issue (along adding Apple Cash to Pay, although Apple's backend server support is not yet live - as of this writing). I recommend completing the update rather than the workaround suggested at AppleInsider, particularly their suggestion to toggle Off Auto set for Date & Time.

The issue apparently had to due with local notifications created on-device rather than server based. I had none going into 12/2; so, I didn't see any resulting issues. ...But, I've now completed the 11.2 update.

Here's the iOS 11.2 Update Support Page

It's not been a good week at Apple Software Development.

Usually I have to manually initiate iOS updates, but this one (11.2) got installed all by itself ?!?

I'm curious... Was your update completed while your iPhone was connected to power?

I think Apple has been auto-updating (background push) certain, critical updates. [I wan't aware such was the case with this iOS update, or any of the macOS updates appearing this week, as I completed it manually.] ...This isn't typical, but I sense Apple has been willing to risk upsetting some users, in favor of completing these updates PDQ.

Although iOS 11.2 was officially released some days ago, iOS 11.2 public beta 6 was only released to beta testing yesterday afternoon so development of 11.2 is apparently still ongoing

According to the 11.2 Update Support Page, 11.2 was made public on 12/2. (The Beta has been around for a bit, as I had read it would provide Cash.)

Here's more on 11.2 at MacRumors

This weekend update is atypical and probably represents how quickly Apple wanted to get this update behind them on a non-news day.

Public Beta 6 was released 12/2 also — Perhaps Public Beta 6 is the Gold Master? Thinking back that may have happened with iOS 11.1 beta as well.