Following the release of iOS 11.3.1 last week, Apple has stopped signing iOS 11.3, which was the previous publicly available version of the mobile operating system.
This is a routine move on Apple’s part, as it is common practice for the Cupertino firm to stop signing older operating system versions once a new version has been publicly released. This encourages users to keep their operating systems up to date.
So, if you’ve already upgraded your device to iOS 11.3.1 you won’t be able to go back to an earlier version of iOS.
The iOS 11.3.1 update included the following:
iOS 11.3.1 improves the security of your iPhone or iPad and addresses an issue where touch input was unresponsive on some iPhone 8 devices because they were serviced with non-genuine replacement displays.
Note: Non-genuine replacement displays may have compromised visual quality and may fail to work correctly. Apple-certified screen repairs are performed by trusted experts who use genuine Apple parts. See support.apple.com for more information.
The iOS 11.3.1 update can be downloaded on all compatible devices by going into the Settings app and tapping “General” -> “Software Update.”