Even though jailbreaking is now legal, the cat and mouse game will never stop between Apple and the jailbreak community. Last example is the fact that iOS 4.2.1 has introduced a new baseband requirement, as explained by Notcom, the developer of TinyUmbrella.
While it’s not clear yet what Notcom means by “baseband requirement”, we can nonetheless assume that it is some kind roadblock that’s going to make it harder for us to jailbreak, unlock, and downgrade.
Here is what Notcom has to say about this new baseband requirement:
It seems that Apple has decided to put a baseband requirement on iOS. So at this point, if you are using Saurik’s server or tiny umbrella and trying to restore 4.2.1 on an iPhone 4, you will end up in recovery mode and tiny umbrella will not be able to pull you out of recovery. In this case, you will have to restore 4.1 again or you will have to restore 4.2.1 stock and be tether jailbroken. (Of course, I recommend 4.1 and not bothering with 4.2.1 at all). If you are an unlocker, this is a no brainer. Do not update to 4.2.1 even to test it at this point.