Users with iPhone and iPads running iOS 8 or earlier can no longer backup their device to iCloud. Apple in November announced the change and it has now gone into effect.
Support for iCloud backups on devices running iOS 8 or older is no longer available, and Apple has deleted all existing iCloud backups of devices running the older versions of iOS. If the device is able to be updated to iOS 9 or later, users can once again begin backing up the device to iCloud. If the device cannot be updated to a later version of iOS, users can still backup the device to a Mac or Windows PC.
Apple says it turned off iCloud backups for devices running older versions of iOS to “more closely align” with Apple’s “published minimum software requirements.”
With the iOS 9 update that came out several years ago Apple adopted CloudKit for iCloud backups and stopped using an older system, which is the system that was sunsetted this week.