Apple Ceases Signing iOS 7.1.2, Downgrading No Longer Possible [iOS Blog]
As of today, Apple has stopped signing the iOS 7.1.2 firmware, which will prevent users from downgrading from iOS 8 back to iOS 7 (via iClarified). This means that users who are unhappy with the changes that iOS 8 have brought or unsatisfied with bugs introduced with the update will be unable to downgrade back to iOS 7.1.2.
Apple’s decision to stop signing iOS 7.1.2 is not unusual, as the company often stops signing prior versions of iOS shortly after the release of a new version of iOS. iOS 8, the latest Apple mobile operating system, was released to the public on September 17.
iOS 7.1.2 does, however, remain available for iPhone 4 users, as the iOS 8 operating system can only be installed on the iPhone 4s and later.
Released on June 30, iOS 7.1.2 is the latest version of iOS 7, which included minor bug fixes, security improvements, and a fix for an email attachment encryption issue.