Other Other Other Note: There is an new bootrom exploit for A5 to A11 devices called checkm8. Other Other Note: There is an even newer method of downgrading/upgrading that will allow almost all 32-bit devices (doesn't include the 32-bit devices that can install iOS 10) to go from iOS 9.3.5 firmware to any other iOS 9.X firmware. Other Note: I am missing information about the original Odysseus which allows a few 32-bit iOS devices to downgrade in the iOS 6 and 7 range. Right now, the best tutorial for Prometheus is by and is endorsed by the author of Prometheus, I will be updating this answer later to explain more about it, but I wanted to get this information posted here sooner rather than later. The biggest caveat to this tool is that you must be jailbroken in most cases before initiating the restore (and you only have one shot, so a failed restore will force you to install a signed firmware) (if that signed firmware is also jailbreakable, then technically you get second chances, but it's rare for that to be the case unless there's a bootrom exploit for your device). The tool for it is called futurerestore (codenamed Prometheus). Note: There is a new method of downgrading/upgrading that doesn't require Apple to be currently signing, and it works on newer devices that aren't present in the first list of my answer below.

This wikipedia page contains a list of iOS devices & the latest iOS they can support. See this article for some general information around this topic. If you had previously Jailbroken your device on iOS 6, it may be possible, providing you have saved your 'SHSH blobs' which can 'sign' the install instead of Apple. Once a new version comes out, Apple stops signing previous releases to keep everyone running the same iOS version and to prevent you from jailbraking your device again after restoring by forcing you to do an update. Putting a newer iOS on older hardware that never even supported that OS is near impossible.Īs part of the iOS restore process, iTunes has to check with Apple's servers to 'sign' each install of iOS just like App Store apps must be signed to run. This signing window typically is closed within days of a new version shipping. Downgrading or upgrading to a no longer current version of iOS is generally not possible once Apple stops signing the old software, as is needed when iTunes is preparing to install or restore an iOS.

Instal the new version for ipod