Downgrading to iOS 8.1 no longer possible
About a couple of weeks after releasing iOS 8.1.1, which came along with several bug fixes plus increased stability and performance improvements for the iPad 2 and iPhone 4S, the company has stopped signing iOS 8.1. This just means that users will not be able to downgrade or restore to the previous firmware version.
The change in the signing status of iOS 8.1 will be confirmed on the popular third-party iOS firmware database IPSW Downloads -- the iOS 8.1 page on the website now shows red ‘!’ icons instead of green check mark icons.
If you prefer your device jailbroken, you’ll be pleased to know that iOS 8.1.1, which is compatible with the iPhone 4S upwards, iPad 2 and newer, and the 5-generation iPod touch, is jailbreakable as well.