These errors are received while users try to restore a custom firmware using softwares like Sn0wbreeze, by putting the iOS device in a pwned state.
iReb is a Windows only tool and other than bypassing iTunes errors, it also helps to fix recovery Mode loops.
The latest version, iReb R6 adds support for the latest firmware iOS 6.x.x running on the pre-A5 devices that includes iPhone 3GS and iPhone 4. It won’t support the latest devices including iPad 3, iPad 4, iPhone 4S or iPhone 5. So do not bother trying it with the latest devices.
Those who want to preserve their baseband while upgrading to iOS 6 to keep using unlocked iPhone 4 and iPhone 3GS can use this program if they are facing any iTunes errors.
iH8sn0w is a jailbreak community member who works on Windows jailbreak tool and that is the reason we don’t have the same version of the program for Mac users.