https://techcrunch.com/2018/08/31/apples-new-ios-12-beta-fixes-the-annoying-please-update-bug/

iOS 12 beta testers have been plagued with a frustrating bug that continually pops up messages alerting them that a new iOS update is available when, in fact, it’s not. Apple has now fixed this bug, which is patched in the latest iOS 12 betas rolling out now, we understand.

The bug first made headlines on Thursday, when a number of iOS 12 beta testers – including developers and those on the public beta program – began to complain on social media about the problem. All users were seeing a pop-up message that read, “A new iOS version is now available. Please update from the iOS 12 beta.”