Upgrade Iphone 4 version to 4.2.1, Itunes Return Error 1013 warning!

I've wanna try to jailbreak my new Iphone 4, with version 4.2. I have save my device SHSH with TinyUmbrella application. And it makes a big problem for me.

I wanna use redsn0w 0.9.6b4 to jailbreak my iphone, and i have download a 4.2.1 firmware, coz i have see at SHSH saved file (the result of TinyUmbrella application), and it show the version 4.2.1. but i have wrong.. my version only 4.2.

So the problem is, when i wanna restore from itunes, at finish it show some warning with error code 1013. So, if You have a same problem with Me, You can follow the direction here

Or you can read the direction bottom here :

On Mac:
* Open Finder
* Hold down COMMAND + SHIFT keys and press 'G'
* Enter "/private/etc/" in the field and press "Go"
* Find "hosts" file in the directory
* Drag the file to your desktop
* Open it in text editor
* Remove the line that has gs.apple.com entirely or put a # at the beginning of it to comment it out
* Save the file
* Drag it back to the /private/etc/ folder.
* You'd need to enter your username and password to authenticate the move

On Windows:


Locate the hosts file in one of the following directories:
Windows 95/98/Me c:\windows\hosts
Windows NT/2000/XP Pro c:\winnt\system32\drivers\etc\hosts
Windows XP, Vista, 7 c:\windows\system32\drivers\etc\hosts

Right click and click on "Open With..." and then click on "Notepad" on the list.
* Remove the line that has gs.apple.com completely and save the file.

This should work fine but you will lose all music, photos, videos and books :S

Thanks to user KianABC

Reference : Apple