Apple has been releasing iOS 27 for about a week. After stopping verifying iOS 26.6, the company no longer allows users to install this version on iPhones upgraded to iOS 27.
Apple uses a server authentication mechanism for iOS versions. Only versions that are still authenticated by Apple with a digital signature can be installed. When Apple stops signing a software version, users cannot install or restore the device to that version.
This approach helps Apple limit users from returning to old iOS versions, which may lack new security patches.
If you have not upgraded to iOS 27, users can still continue to use iOS 26. However, after updating to iOS 27, returning to iOS 26.6.2 is no longer possible.
Users also cannot downgrade from iOS 27 to iOS 26.7, the version released with iOS 27. According to MacRumors, iOS 26.7 is provided as a network update (OTA) and there is no recovery file for users to downgrade.
