iPhone developer iH8sn0w has just released a new version of iREB which is compatible with all iOS 4.2.1 devices. You can use it to bypass 1604, 1603, 1602, 1601, 1600 error in iTunes during custom iOS 4.2.1 firmware restore which has been created using either Sn0wbreeze or PwnageTool.

Some of you might have noticed the annoying 1604, 1600 error when restoring to iOS 4 custom firmware in iTunes which is built using PwnageTool 4.0 or 4.01. The error in question looks something on the lines of this.

I have got loads of emails and queries via comments on the posts here and here where many of you have been asking on how to fix 1604, 1603, 1602, 1601, 1600 error in iTunes during firmware restore. This error is occurred when you are trying to restore your jailbroken custom iPhone 3.1.3 .ipsw file which you cooked using either PwnageTool or sn0wbreeze.