An upcoming version of redsn0w will allow users to downgrade an iPhone, iPod touch, or iPad from one version of iOS to an earlier version.
Redsn0w is one of the most popular tools for jailbreaking iOS devices, but the utility also includes a number of other tools which let you save SHSH blobs, get out of recovery mode if your phone or tablet is stuck, or make other changes.
Now iPhone Dev Team member Musclenerd says a new version of the tool will support downgrades.
This can come in handy if you accidentally update your operating system and want to roll back to an earlier version for some reason.
For instance if you have an iPhone that’s been unlocked to work with different carriers or you have an untethered jailbreak, updating to a new version of iOS may limit support for those features.
Users will need to manually save SHSH blobs in order to use the new feature, which means now is as good a time as any to start backing yours up.