Did u have your shsh blobs backed up?
iTunes asks your phone to send a few small packets of data (SHSH blobs) to apple's servers. Then, if everythings ok, they get 'signed' and sent back to iTunes. iTunes will only up/downgrade or restore a iPhone if it has these signed blobs. As far as I'm aware apple's servers will not sign blobs for phones that are restoring to a older firmware. That's why you need your blobs to downgrade so you can trick iTunes into thinking that they are signed...
I've upgraded to iOS 4.2.1 and I'm facing a lot
Of problems with it.
Can you help me to get my iPhone back to
iOS 4.1
Please help
iTunes will only up/downgrade or restore a iPhone if it has these signed blobs. ..
If your not jailbroken then you don't need to worry about it...