Updating the ipod touch
Please make sure you download the correct i OS 11 firmware file otherwise i Tunes will fail to restore your device. Additionally, you will also learn the best way to save your SHSH blobs which will allow you to downgrade your i Phone, i Pad, i Pod Touch and Apple TV firmware version in the future.What is happening is Apple refuses to generate the new hash during the downgrade, meaning the new SHSH blobs cannot be generated.In case this wasn’t a big enough limitation to downgrading i OS devices, in the i OS 5 firmware generation Apple introduced yet another technology to prevent downgrading called APTickets.You can now download i OS 11 full and final IPSW update for all compatible i Phone, i Pad and i Pod touch devices.We have the complete changelog of the update in one place too.These blobs are essentially gatekeepers and control whether or not a firmware is restorable.Whenever you upgrade or downgrade your i Phone, i Pod Touch or i Pad, new SHSH blobs have to be generated because one of the parts to the SHSH formula is the firmware version.
In the future APTickets will completely replace SHSH blobs, this will happen once the i Phone 4S stops being supported.
Downgrading your i Phone, i Pod Touch or i Pad to a lower firmware version is indeed possible, but unfortunately has become harder and harder over the years.