Note: click here if you’re looking for iOS 5 upgrade error 3002.
While trying to upgrade your iPhone OS from firmware 3.x (probably 3.1.3) to iOS 4.0 you would have received the error: 3002 just like I did. Well the error message said:
The iPhone “nabphone” could not be updated. An unknown error occurred (3002).
Pretty annoying. . . isn’t it? tried again to upgrade but no use! Ah well… then how to fix this 3002 error while upgrading iPhone firmware from 3.x to 4.0? simple! Read along!
This error occurred when you try to upgrade your iPhone OS firmware to iOS 4.0 (or any other in your case maybe too). Then how to fix this issue? Use the restore instead of upgrade. Yeah! restore and it will do the same thing as it does in upgrade, provided that it will not give this error.
You can download the ipsw for your iPhone model and then restore by shift restore in windows / alt restore in mac
Isn’t it funny that this error comes with the latest 9.2 version of iTunes! I mean oh comeon! you released 9.2 for the purpose of upgrading iOS 4.0 and it gives errors and bugs! dude! do you even check what you release before you make it public? Or maybe they kept this error there intentionally for the user with jailbroken and / or unlocked iPhones? (don’t know if any normal user faced this error in this situation too).
Update: It happens to non jailbroken iPhone / iPod users too. (thanks to Nikhil)