This device is not eligible for the requested build: Also sometimes displayed as an "error 3194." If you receive this alert, update to the latest version of iTunes. Third-party security software or router security settings can also cause this issue. To resolve this, follow Troubleshooting security software issues.
Downgrading to a previous version of iOS is not supported. If you have installed software to performunauthorized modifications to your iOS device, that software may have redirected connections to the update server (gs.apple.com) within the Hosts file. First you must uninstall the unauthorized modification software from the computer, then edit out the "gs.apple.com" redirect from the hosts file, and then restart the computer for the host file changes to take affect. For steps to edit the Hosts file and allow iTunes to communicate with the update server, see iTunes: Troubleshooting iTunes Store on your computer, iPhone, iPad, or iPod—follow steps under the heading Blocked by configuration (Mac OS X / Windows) > Rebuild network information > The hosts file may also be blocking the iTunes Store. If you do not uninstall the unauthorized modification software prior to editing the hosts file, that software may automatically modify the hosts file again on restart. Also, using an older or modified .ipsw file can cause this issue. Try moving the current .ipsw file, or try restoring in a new user to ensure that iTunes downloads a new .ipsw.
The required resource cannot be found: This alert message occurs when your device has a newer version of iOS than what is available in iTunes. When troubleshooting a device that presents this alert message, go toSettings > General > About and check the version of iOS on the device. If it is newer than the latest released iOS version, the device may have a prerelease developer version of iOS installed. Installing an older version of iOS over a newer version is not supported.
Error 3194: Resolve error 3194 by updating to the latest version of iTunes. "This device is not eligible for the requested build" in the updater logs confirms this is the root of the issue. For more Error 3194 steps see: This device is not eligible for the requested build above.