So the error is that when you try to upgrade your iPhone to iOS 5 it gives error 3002.
I haven’t upgraded my iPhone to iOS 5 yet, but I will share the solution that worked for iOS 4 upgrade, might help (and should too) in upgrading your iPhone to iOS 5 successfully and avoinding the iphone 3002 error.
How to fix iPhone iOS 5 upgrade error – 3002
Solution is to “restore”
Thats right, you can download iOS 5 from internet and simply use the “shift + restore” button to select the downloaded ipsw file for your device.
After restoring it, it will be same as upgrading your iPhone and you won’t get any such error.
I don’t know why apple releases software without thoroughly testing them! comeon!