How to Fix iTunes Error 1639 When Restoring or Updating iPhone

By ErrorFix · Updated October 24, 2026 · 8 min read

What error 1639 means

Error 1639 is an iTunes or Finder error that appears while an iPhone is being restored or updated. The process starts, iTunes or Finder downloads or prepares the iOS software, and then it stops with a message that the iPhone could not be restored and an unknown error occurred (1639). Your iPhone is usually left in recovery mode, showing the computer-and-cable screen.

Apple groups error 1639 with errors 17, 3000–3020, 3194, and 3100–3999. Every code in that family means the same thing at its core: the computer could not communicate with Apple’s software update servers. During a restore, the computer has to contact gs.apple.com to verify that the iOS version being installed is genuine and currently signed by Apple. If that handshake fails for any reason, the restore is stopped rather than allowed to continue with unverified software.

That mechanism is also why error 1639 is rarely a hardware problem. The iPhone itself is usually fine; something between the computer and Apple’s servers is in the way. The usual suspects are a hosts-file entry redirecting gs.apple.com elsewhere, a firewall or antivirus tool blocking the connection, a filtered network such as a workplace or school connection, outdated iTunes or Finder software, or a temporary outage on Apple’s side. Work through the steps below in order and you will find the blocker quickly.

Common causes

• Hosts-file entry blocking gs.apple.com: the classic cause — often left behind by old jailbreaking or downgrading tools that redirected Apple’s servers.
• Firewall or antivirus interference: security software blocking iTunes or Finder from reaching Apple’s update servers.
• Filtered or unstable network: workplace, school, or public networks that block Apple’s domains, or a flaky connection that drops mid-restore.
• Outdated iTunes, Finder, or computer OS: old software versions that mishandle the restore handshake with Apple’s servers.
• Unsigned iOS build or Apple server outage: requesting an iOS version Apple no longer signs, or restoring while Apple’s servers are down.

How to fix error 1639 — step by step

Start with the easy wins — updates and networks — before touching the hosts file. Work down the list in order.

1. Update iTunes, Finder, and macOS, then retry. On Windows with the Microsoft Store apps, open the Microsoft Store > Library and install updates for the Apple Music and Apple Devices apps (in classic iTunes, go to Help > Check for Updates). On a Mac with macOS Catalina or later, restore from Finder and open Apple menu > System Settings > General > Software Update. Restart the computer afterward and try the restore again, since an outdated app is one of the simplest causes of error 1639.
2. Confirm the internet connection and try another network. Make sure the computer can browse the web normally, then restart the router and modem if anything seems slow or flaky. If the restore still fails, switch networks entirely: try a phone hotspot or a different Wi-Fi network. A workplace or school network with filtering in place can block Apple’s servers, and a different network immediately tells you whether your network or your computer is the problem.
3. Temporarily disable firewall and security software. Antivirus programs, firewalls, and endpoint-protection tools can block iTunes or Finder from reaching gs.apple.com, which is a documented trigger for error 1639. On Windows, go to Windows Security > Virus & threat protection > Manage settings, and temporarily turn off real-time protection and the firewall. Retry the restore immediately, then re-enable everything as soon as the attempt finishes.
4. Check and clean the hosts file. On Windows, open Notepad as administrator and open C:\Windows\System32\drivers\etc\hosts. On a Mac, open Terminal from Applications > Utilities and run sudo nano /private/etc/hosts, then enter your password. Look for any line mentioning gs.apple.com: if one is present, add a # character at the start of the line to comment it out, or delete the line entirely. Save the file, restart the computer, and retry the restore.
5. Try a different computer, cable, and port. Connect the iPhone to a different computer with a fresh iTunes or Finder install, using a genuine Apple or MFi-certified cable plugged directly into the computer with no USB hubs, keyboard ports, or extension dongles in the chain. If the restore completes on the second computer, the original computer’s network settings, security software, or iTunes installation was the problem, not your iPhone.
6. Restore from recovery mode with the latest iOS. Put the iPhone into recovery mode, connect it to the computer, and choose Update first: this reinstalls iOS without erasing your data. If Update fails with 1639 again, choose Restore, which wipes the iPhone and installs the latest signed iOS version. If error 1639 still appears after a clean restore on a second computer and a second network, contact Apple Support, since the problem may be on Apple’s side or with the device itself.

Did this fix it? Quick checklist

• iTunes or Finder and the computer’s OS fully updated
• The computer reaches Apple’s servers on a different network (hotspot test passes)
• No gs.apple.com line left in the hosts file, firewall and antivirus re-enabled after the test
• The restore or update completes without 1639 (or Update in recovery mode succeeds)

If 1639 survives updated software, a clean hosts file, a second network, and a second computer, stop retrying the same setup — the pattern points away from your equipment. Check Apple’s System Status page, confirm you are installing the latest signed iOS version, and contact Apple Support with error 1639 in hand; it places your case straight into the server-communication family of restore errors.