Apple Stops Signing iOS 8.4.1 and iOS 9.0

Following the release of iOS 9.0.2 on Wednesday, Apple stopped signing iOS 8.4.1 and iOS 9.0 firmware for compatible iOS devices. The move prevents users from downgrading from iOS 9.0.2.

AppleInsider:

As expected, Apple has taken steps to ensure iOS device owners have the latest and most stable version of its mobile operating system, and is no longer signing code for iOS 8.4.1 or iOS 9.0. The company is limiting compatible versions to iOS 9.0.1 and iOS 9.0.2, the latter of which as released earlier today.

What this means to users is users who have upgraded to iOS 9.0.2 can no longer revert back to iOS 8.4.1 or iOS 9.0.

Apple released iOS 9.0.2 on Wednesday, which addresses the following issues:

• Fixes an issue with the setting to turn on or off app cellular data usage
• Resolves an issue that prevented iMessage activation for some users
• Resolves an issue where an iCloud backup could be interrupted after starting a manual backup
• Fixes an issue where the screen could incorrectly rotate when receiving notifications
• Improves the stability of Podcasts

Although not listed in the bug fixes, the security notes for iOS 9.0.2 say the update also fixes the Lock Screen vulnerability that allowed bad guys to bypass the lock screen and access photos and contacts on a locked device. That exploit had been discovered in iOS 9, and had not been patched in iOS 9.0.1.