How to Fix iTunes Unknown Error 1013

Background: The restoring or upgrading process of iPhone, iPad and iPod Touch may be stopped by the occurrence of "an unknown error 1013".


And your device may even tells "connect to iTunes".


Reason: This error might occur because of connection to gs.apple.com is blocked, redirected or suspended.

Solution:
Adjust hosts file or other security software and make sure the connection to gs.apple.com is ok. If it remains the same, try other computer with good network environment. if ok after you change the computer, try to ask help from administrator who offers support to your computer system or installation of the security software.
If hosts file redirects request to gs.apple.com, you can follow instruction of "Hosts file may block iTunes Store" from "Unable to connect to iTunes Store".
Please refer to this http://support.apple.com/kb/TS3694#error1013
Details for editing the hosts file:
Open C:\Windows\System32\drivers\etc\


Right click "hosts" → "open in notepad", delete 74.208.10.249 gs.apple.com then save and exit.


If access denied, right click "hosts" → "property" → "security" → "edit", tick "Full control" then again go back to change the IP.




Restart your computer after editing and it should be ok.