Apple today quit signing iOS 8.4.1 and the first variation of iOS 9 for the iPhone, iPad, and iPod touch, meaning customers can no longer update or downgrade to these editions of iOS using iTunes. Apple is presently signing iOS 9.0.1 and iOS 9.0.2 just.
Users that have updated to iOS 9 are now unable to downgrade back to-the-last variant of iOS 8, iOS 8.4.1. Launched in August, iOS 8.4.1 was a small update that contained bug fixes and Apple Audio progress. iOS 8.4.1 also broke the iOS 8.4 untethered jailbreak.
iOS 9 was first introduced to the community on September 16, and there there were two added upgrades since that point. iOS 9.0.1 was launched on September 23 and iOS 9.0.2 was introduced on September 30.