Dev Team Releases Redsn0w 0.9.11b1:Downgrade Your iPhone 4S, iPad 2, New iPad [update: Redsn0w 0.9.11b2]

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As expected, iPhone Dev team have just released a new version of Redsn0w, which allows users who may have accidentally upgraded to iOS 5.1, to downgrade to iOS 5.0.1.

Until now it was possible to downgrade only iPhone 3GS, iPhone 4, iPad 1, iPod touch 4G and iPod touch 3G from iOS 5.1 to iOS 5.0.1 using the SHSH blobs saved using TinyUmbrella.

But with Redsn0w 0.9.11b1, iPhone 4S, iPad 2 and iPad 3 users will be able to downgrade their iOS device if they’ve saved their SHSH blobs. This has been possible due to a hack that allows A5 downgrades without a bootrom-level exploit.

Downgrading to iOS 5.0.1 will allow users to perform the untethered jailbreak using Absinthe jailbreak. Unfortunately, users who have recently purchased their iOS device that come pre-installed with iOS 5.1 won’t be able to downgrade as personalized SHSH blobs is required for the downgrade process.

We’re not sure if you can downgrade from iOS 5.1.1, but since Dev team has mentioned it supports iPad 3 as well, which came pre-installed with iOS 5.1, we’re assuming it does work. We’ll update the post as soon as we get a confirmation.

Dev team has provided the following information on their blog:

  • The new feature is at Extras->Even More->Restore
  • You cannot downgrade without the personalized SHSH blobs for your device at that lower firmware.  You need to have fetched those blobs while the signing window was open, using either Cydia’s built-in [email protected] feature, or with TinyUmbrella.  The new Restore screen of redsn0w lets you choose either the remote blobs or local ones (for the earlier firmware).  If you don’t know where TinyUmbrella put your blobs, TinyUmbrella has a button that will show you (copy them out of that folder and feed them to redsn0w).
  • The A5 downgrade method actually updates to the latest firmware before downgrading to the earlier one. This process updates your baseband to whatever is newest.  DO NOT USE THIS METHOD IF YOU RELY ON UNOFFICIAL UNLOCKS of your iPhone4S.  Those who used the temporary SAM technique to unlock their iPhones to specific SIMs shouldn’t be affected by this baseband update.
  • This method can be fixed by Apple with a firmware update.  It’s a (pleasant) mystery why they haven’t fixed it yet, because reverse-engineering of the restore ramdisk indicates they do know about it.  It’s possibly too niche to bother to fix right now.
  • The least-tested devices with this method are the iPad2,3 and iPad3,2 (because we don’t have those models).  If you do and you feel like experimenting, please let us know how it turns out in the comment section below!
  • This update involves a bunch of new redsn0w code.  We recommend sticking to the previous version 0.9.10b8b unless you’re specifically using this new feature, until all the bugs are worked out!  (Note: If redsn0w gets stuck at the “Waiting for device” stage for more than 30 seconds, you’ve hit a pesky GUI bug…that will be fixed in an upcoming version!)
We’ll soon post a step-by-step guide on how to downgrade to iOS 5.0.1, but if you want to give it a shot, you can download Redsn0w 0.9.11b1 for Mac using this link and Redsn0w 0.9.11b1 for Windows using this link (be sure to run in Administrator mode).
Update: iPhone Dev-team has just released Redsn0w 0.9.11 b2 to bring support for “9A406″ version of 5.0.1 for iPhone4S.
Redsn0w 0.9.11 b2 : Mac | Win