So for whatever reason you went ahead and updated your iPhone to iOS 4.3.4 in iTunes. Normally this is no problem, except for the fact that your want to jailbreak your device untethered. Turns out an untethered iOS 4.3.4 jailbreak solution doesn't exist right now. Is there any way to return to iOS 4.3.3 and jailbreak?
According to the latest research by iPhone Dev-Team Apple has taken steps to make iOS 5 more difficult to jailbreak and downgrade. Although the limera1n exploit used for iOS 4.x jailbreaks still works in beta iOS 5, only a tethered jailbreak is possible at this time. Starting up a jailbroken iPhone tethered requires that the device be connected to a computer while booting.
It's not clear if Apple's move can be countered in the near future, as the company will begin to generate a unique APTicket every time the iPhone is restored. Not only this, but the APTicket will be verified every time the device is turned on.
Sometimes for whatever reason an iPhone firmware upgrade ends up being counterproductive or causes issues with your individual phone. Maybe you're experiencing battery life problems with iOS 4.1 on your iPhone 3GS. Updates can even happen by accident with the wrong click of a button, wiping a jailbroken device.
If you have already saved your SHSH files for one or more earlier firmware versions on Saurik's server, you can follow these steps to downgrade from iOS 4.1.
First of all, downgrading your iPhone firmware is only possible if you have saved your SHSH files. For those who took this precautionary step, use these instructions to downgrade.
Note that downgrading your iPhone firmware is only possible if you have saved your SHSH files. For those who prepared by taking this step before upgrading, see the following instructions to downgrade.
First download your SHSH files to your computer with TinyUmbrella.
1. Install TinyUmbrella.
2. Plug in your iPhone and run TinyUmbrella.
3. In TinyUmbrella select Advanced Options and choose 4.0.1 firmware.