- Apr 12, 2001
Customers who have upgraded to iOS 10.3.1 will no longer be able to downgrade their devices to iOS 10.2.1 or iOS 10.3.
Apple routinely stops signing older versions of software updates after new releases come out in order to encourage customers to stay up to date.
iOS 10.3.1 is now the only version of iOS 10 that can be installed on iOS devices by the general public, but developers and public beta testers can also download iOS 10.3.2, a future update that is currently being beta tested.
Article Link: Apple Stops Signing iOS 10.2.1 and iOS 10.3