On December 20, 2023, Apple released the iOS / iPadOS 17.2.1 update for fans, version number: 21C66.
Apple has closed the verification channel for iOS / iPadOS 17.2, and fans are no longer able to downgrade to the relevant version.
In order to encourage fruit fans to update the operating system of the device in time and ensure the security of the system.
Apple usually closes the verification channel for older versions of iOS after a new version is released to prevent fans from downgrading to an insecure version.
And in the latest iOS/iPadOS 17.2.1, Apple mainly fixes the problem that the battery drains faster than expected in some cases.
In addition, some iPhone 15 fans reported that they could not connect to the carrier signal after upgrading to the relevant version, resulting in problems such as not being able to make calls or using cellular data.