Apple has officially stopped to issue digital certificates to iOS upgrade 9.1. From this moment users of iPhone and iPad there is no possibility to roll back to the previous version of the operating system with iOS 9.2.
The release of the software platform iOS 9.1 took place in late October. Most of the changes it has remained “under the hood”, and normal users will not notice a tangible difference. The structure of automatic update includes new APIs that simplify working with Live Photos, and also run the 3D Touch. In OS added a new set of emoticons (over 150), the Unicode Consortium introduced in the eighth edition of the Unicode. Also you can find setting for “Show contact photos” in the app Message.
Recently Apple made a point of signing older firmware for a couple of weeks after the release of the new. This time period was a big “window” was closed two months later, the company stopped issuing digital certificates Tuesday, December 22.
Now Apple is not signing iOS 9.1 for any compatible devices. This means that users cannot roll back from a newer iOS 9.2 or updated to it from earlier releases. This is evidenced by the status of the asset on the service Tssstatus.
Current iOS version is 9.2. The update fixes a number of bugs and software platforms, as well as improves performance. The main changes are enhancements to Apple’s proprietary streaming Music, updating software component Safari View Controller, support 3D Touch for iBooks, Mail Drop in the mail to send attached files of large size.
Currently Apple is testing iOS 9.2.1 iPhone, iPad, iPod Touch with bug fixes.