Apple's decision to halt iOS 7 firmware signing is part of the natural progression toward a wider iOS 8 rollout for compatible devices, which include the iPhone 4S and above, iPad 2 and above and both iPad mini models. The change was noted by developer Steven Troughton-Smith via Twitter earlier today and confirmed by multiple sources, including popular third-party iOS firmware database IPSW Downloads.
With Apple no longer performing iOS 7 code signing, users who previously upgraded to the latest iOS 8 version can no longer revert to the last-generation OS. As noted above, owners of non-compatible devices like the iPhone 4 and original iPad still have access to the firmware.
The last iOS 7 version to see release came in June with iOS 7.1.2, which brought fixes for issues found in Mail, iBeacon and barcode scanner accessories.
Apple released the latest iOS 8 operating system for public consumption last week, bringing a slew of new features to iPhones and iPads, including app extensibility, support for Continuity, new messaging options and more. The launch also came with a HealthKit bug, however, prompting Apple to pull apps that connect to the framework as it researched a fix.
The company promised a patch and subsequently pushed out the iOS 8.0.1 maintenance update on Tuesday, but that release also contained bugs. Limited to the iPhone 6 and 6 Plus, iOS 8.0.1 disabled cellular connectivity and Touch ID drivers for many users. Apple's most recent iOS 8.0.2 version appears to fix the aforementioned problems, though some iPhone 6 users in Australia are still reporting trouble with cell networks.