WHOA! Redsn0w 0.9.11b1 to downgrade to previous iOS firmware for iPhone 4S, iPad 3 and iPad 2 has been just released by Musclenerd. The method uses a new hack that allows A5/ A5X downgrades without a bootrom-level exploit. Redsn0w 0.9.11b1 download is available for windows as well as mac users which downgrades iOS 5.1 / 5.1.1 to iOS 5.0.1/ 5.1.
The most important requirement of redsn0w to downgrade is to have saved personalized SHSH blobs for the firmware you want to restore to on your device. The SHSH blobs can only be saved when the window for the firmware is open. So, if you already have saved SHSH blobs of iOS 5.1 or iOS 5.0.1 with TinyUmbrella or redsn0w can downgrade from iOS 5.1 to iOS 5.0.1 and iOS 5.1.1 to iOS 5.1.
NOTE [MOST IMP]: The hack used in redsn0w 0.9.11b1 to downgrade requires the device to first upgrade to the latest firmware and baseband. So, users who rely on official or unofficial unlock MUST NOT use this method, as they can loose their unlock.
To downgrade your device, when you run redsn0w, you will see a new set of options (under Extras -> Even More-> Restore) available with Local Restore and Remote Restore. Local blobs will use those SHSH blobs that are saved into your machine and Remote option will allow you to use SHSH blobs that are saved in Cydia. You can select the location according to your saved SHSH blobs location to proceed.
Musclenerd also says that, Apple can patch this new method easily, so better to downgrade as soon as possible. Here is the list of points mentioned by Musclenerd on his blog post:
Some important points:
- 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 TSS@Home 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 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!)
You can download redsn0w 0.9.11b1 for mac and windows from the link below. You can use the guide here to downgrade your iPhone 4S, iPad 3 and iPad 2 to older firmware.
Download Redsn0w 0.9.11b1 to downgrade iOS Firmware:
[UPDATE 1]: Musclenerd notes,
We accidentally left out one of the two flavors (“9A406”) of 5.0.1 for iPhone4S. It’ll be in the next update, but in the meantime check if Cydia or TU saved your blobs for the other 5.0.1 for iPhone4S (“9A405”).