- Error 17
- Error 1639
- Errors 3000-3020
- Error 3194
- Errors 3100-3999
- This device isn't eligible for the requested build
If you see one of these messages and need help updating or restoring your iOS device, install the latest version of iTunes and try to update or restore again. If you still can't update or restore, follow the steps below.
Address TCP/IP filtering, firewall, or security software
If you have TCP/IP filtering, firewall, or security software installed on your computer, try these steps.
- Configure or temporarily uninstall your security software.
- Be sure you have a working Internet connection. Try visiting www.apple.com or contact your Internet service provider for more help.
- Bypass your Internet router. Some routers might block iTunes from accessing the update server. If you're using a router that isn't manufactured by Apple, try the following:
- Disconnect from your wired or wireless router and use an Ethernet cable to connect your computer directly to your modem.
- Restart your computer and modem. Contact your Internet service provider for instructions on using your modem.
Restore or update from another computer
Try to restore or update on another computer with a different Internet connection. This helps to make sure there aren't issues with your computer that might stop iTunes from communicating with the update server.
Errors 1639, 3000-3020, and 3100-3999 (with the exception of 3194) are sometimes caused by your network settings. If your computer uses a managed network, refer to your network administrator. Proxies, firewalls, and other network security measures can cause these errors. If necessary, find a different network connection to restore the device. For example, if you're restoring at work, try to restore at home or on a friend's computer and network.
Check your hosts file
After you update iTunes to the latest version, check the hosts file to make sure your computer can contact the update server.
If you’re using a Windows computer, follow the steps from the Microsoft support site. Resetting the hosts file affects software services that rely on hosts file redirects. If you're using Windows on a business computer, consult your IT department to be sure applications work correctly after you reset your hosts file.
If you're using a Mac, follow these steps:
1. In the Finder, choose Applications > Utilities.
2. Open Terminal.
3. Type this command and press Return:
sudo nano /private/etc/hosts
4. Enter the password you use to sign in to your computer and press Return. You won't see text appear in the Terminal window when you type your password.
5. Terminal displays the hosts file. If you don't see a window similar to the one below, make sure you're using a nonblank administrator password.
6. Navigate using the arrow keys and look for an entry containing “gs.apple.com”.
If you don't see any entry containing gs.apple.com, then the hosts file isn't related to the issue. Close the Terminal and move on to the next section of this article, "Address TCP/IP filtering, firewall, or security software."
7. Add the # symbol and a space ("# ") to the beginning of the gs.apple.com entry.
8. Press Control-O to save the file.
9. Press Return when asked for the filename.
10. Press Control-X to exit the editor.
11. Restart your Mac.