Jailbreak tools such as iREB or TinyUmbrella make changes in host file of your MAC or Windows OS computer and when you try to upgrade firmware on iPhone, instead of Apple’s server iTunes goes to connect to Cydia’s server. As the Cydia bend down its server and there are no specific signing keys for firmware that you are going to install and then iTunes error 1013 occurs.
You can fix this error by using TinyUmbrella and yes it is the same tool that has brought this error. Follow below steps if you also got this error during your iPhone 4 update.
- Go to browser and download TinyUmbrella.
- To explore TinyUmbrella in Windows 7 or Vista you need to make few steps. Right click on TinyUmbrella exe file, select properties and from “Compatibility” tab, click on “Run this program in compatibility mode for”. From dropdown menu, select the option Windows service pack 3. Now choose “Run this program as an administrator” from Privilege level and click “OK”.
- Open TinyUmbrella and click on “Advanced” tab.
- Uncheck the box “Set Hosts to Cydia on Exit”.
Close TinyUmbrella app. Once you are done with all, restart your Windows or MAC OS computer. Your problem would be resolved!