Wondering how to downgrade from iOS 5 to iOS 4? Maybe you rushed out to test your app on the next big thing but now have to deal with a bug in the here and now version, and you don't want to buy an additional device, or maybe you just don't have what you need yet and you'd prefer to wait for a later beta. Either way, it is possible to go back to iOS 4. Last year we showed you how to downgrade from the beta version of iOS 4 as well. I am pleasantly surprised with how good the first beta version of iOS 5 is, but if for any reason you need to go back to iOS 4, we'll show you a couple ways after the break!
I don't recommend downgrading firmware unless you really need to. It can be a painful process that most people won't like dealing with. But if you need to, it is completely possible.
Downgrading via XCode is probably the easiest way to roll back to a previous version of iOS. The bad part is that it can sometimes put you into a never ending DFU loop. You can typically use iRecovery to kick you out of it.
As a side note, PC users can also use iRecovery and libusb if they get stuck in a DFU loop.
You need iTunes 10.5 beta for this, which is also available via Apple's dev portal (and maybe elsewhere if you scan the internet)
You also need TinyUmbrella
This is the route PC users will have to take. Mac users may also choose to do it this way if they don't have XCode or the SDK. Start this process with your device NOT connected to your computer.
If you downgraded successfully using one of our ways (or a different way), let us know how it went in the comments! If you need additional help, check out our TiPb jailbreak forums.
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