Following the launch of iOS 16.0.2 last Thursday, Apple has stopped signing iOS 16 and iOS 16.0.1, the two previously available versions that came out in mid-September. Since the two versions are no longer being signed, it is not possible to downgrade to those versions of iOS after installing iOS 16.0.2.
Apple routinely stops signing older versions of software updates after new releases come out in order to encourage customers to keep their operating systems up to date, so it is not unusual that iOS 16 and iOS 16.0.1 are no longer being signed.
Apple released iOS 16 to the general public on September 12 following several months of beta testing. Key new features include a highly customizable Lock Screen, the ability to temporarily edit or unsend iMessages, improvements to Focus modes, and more. The free software update is compatible with the iPhone 8 and newer.
Apple then released iOS 16.0.1 as a day-one update for the iPhone 14 models to fix bugs including an issue with activation and migration during setup, a problem that could cause photos to appear soft when zooming in in landscape orientation on iPhone 14 Pro Max, and a bug that could cause enterprise single sign-on apps to fail to authenticate.
Although it's no longer possible to downgrade to the earlier versions of iOS outlined above, users can still revert to iOS 15 by connecting to a Mac or PC, thanks to a security fix that Apple issued alongside iOS 16 in the form of iOS 15.7.
