Yesterday Apple released the second beta of iOS 10.3.2 and after this has stopped signing iOS 10.2 and 10.3. Thus, the iPhone and iPad users can no longer roll back to earlier versions of the operating system.
With the release of iOS 10.3, Apple introduced a new file system APFS, which replaced the classic HFS+ from 30 years ago. First APFS allows devices to work faster, faster moves and copies files, it has better resistance to failures, and much more efficiently allocates memory.
The decision to stop the signature of the old versions of iOS is not new, as Apple does so every time after 2-3 weeks after the release of the update. Considering the number of security updates in recent releases, migrating to an earlier version is simply not recommended.
iOS 10.3 brought the user fixes existing bugs, improved security and new features, including APFS, CarPlay Updates and Find My AirPods.
Currently, Apple is testing the iOS update 10.3.2, which does not make changes to the OS interface and contains a minimum of change, they mainly relate to the elimination of errors, increased stability of mobile devices and improve security.