How to Fix iTunes Error 1604 When Restoring iPhone

By ErrorFix · Updated October 20, 2026 · 8 min read

What error 1604 means

Error 1604 appears in iTunes on Windows or Finder on a Mac while you are restoring an iPhone. The restore stops mid-process with a dialog saying the iPhone could not be restored and that an unknown error occurred (1604), leaving the phone in a half-restored state — usually showing the cable-and-computer screen or a black display that refuses to boot. Nothing is confirmed lost yet, but the restore cannot move forward until the failed firmware write is dealt with.

The number points straight at the cause. Error 1604 belongs to the 1600 range of iTunes errors, a family tied to the firmware-flash phase of a restore. Where 1600 fails before the flash can start, 1604 means the write began against a firmware image or a device state that couldn't accept it — the phone wasn't in the deep DFU state the restore demanded, or the IPSW file being pushed was corrupted, mismatched to the model, or unsigned. This is why the error also shows up after attempts to flash custom firmware: the device rejects what it can't validate.

Getting out of it is a computer-side job, and it works in most cases. Enter real DFU mode with the button sequence for your iPhone model, tighten up the USB connection, bring iTunes current, pause security software for the attempt, and feed the restore a fresh official firmware file — error 1604 almost always clears at one of those steps.

Common causes

• Phone not in the right restore state: the phone sits in recovery mode while this restore requires DFU, so the firmware write fails — the classic 1604 trigger.
• Invalid or corrupted firmware file: a half-downloaded IPSW, a file for the wrong iPhone model, or a custom or unsigned image the device refuses.
• USB connection trouble: a worn or uncertified cable, a hub or dock in the chain, or an unstable port corrupting the firmware stream.
• Outdated iTunes or macOS: old software that mishandles the DFU restore handshake and aborts the write.
• Security software interference: antivirus or firewall tools disrupting the low-level traffic to the phone in DFU mode.
• Stale hosts-file entry: a gs.apple.com redirect left by jailbreak or downgrade tools that breaks Apple's firmware signature check.

How to fix error 1604 — step by step

Work through these in order. Error 1604 is a failed firmware write, so the first step — entering genuine DFU mode — fixes the most cases on its own. The middle steps clean up the computer side, and the DFU restore with fresh official firmware at the end is the fallback that clears nearly everything else.

1. Enter proper DFU mode with the correct button sequence. Error 1604 most often means the phone was not in the restore state the firmware expected, so getting into real DFU mode is the fix that resolves the most cases. On iPhone 8 and later: connect the phone to the computer, press and quickly release Volume Up, press and quickly release Volume Down, then press and hold the Side button until the screen turns black — then hold Side and Volume Down together for five seconds, release Side but keep holding Volume Down until the computer reports a device in recovery. The screen must stay black; that is the sign DFU mode worked. On iPhone 7 or 7 Plus: hold the Side button and Volume Down together for eight seconds, release Side, and keep holding Volume Down until the computer detects the phone. On iPhone 6s and earlier: hold the Home and Sleep buttons together for eight seconds, release Sleep, and keep holding Home. Once the computer sees a black-screen device, click Restore and let the firmware install from scratch.
2. Clean up the USB connection. The firmware image is streamed over USB during a restore, and a flaky connection can corrupt the write and keep error 1604 returning even in perfect DFU mode. Use a genuine Apple cable or a certified MFi cable, plug it straight into a USB port on the computer — never a hub, dock, or monitor pass-through — and try a different port, ideally a USB 2.0 one. Unplug all other USB devices while the restore runs, then start the restore again from DFU mode.
3. Update iTunes, Finder, and the computer. An old iTunes build or outdated macOS can mishandle the firmware write that error 1604 is tied to. In classic iTunes on Windows, click Help at the top and choose Check for Updates; with Apple's newer apps, open the Microsoft Store, go to Library, and update Apple Music and Apple Devices. On a Mac, restores go through Finder, so apply pending updates from System Settings, General, Software Update. Restart the computer after updating and retry the DFU restore.
4. Pause security software for the restore. Antivirus and firewall tools frequently meddle with the low-level USB traffic between the computer and a phone in DFU mode, and error 1604 is a familiar result. On Windows, open Windows Security, head to Virus and threat protection, and turn off real-time protection just for the restore window; confirm Apple Mobile Device Service is allowed through the firewall. With third-party suites, switch off their active shields. Switch everything back on as soon as the restore finishes.
5. Delete the cached firmware and pull a fresh official IPSW. A half-downloaded, mismatched, or unsigned firmware file is one of the most common reasons the write fails with error 1604, and it keeps failing no matter how cleanly DFU mode is entered. Force a fresh download: on Windows, delete the IPSW files inside %AppData%\Apple Computer\iTunes\iPhone Software Updates; on a Mac, clear ~/Library/iTunes/iPhone Software Updates. Then re-enter DFU mode, click Restore, and let the computer download an official firmware image for your exact model. The restore wipes the phone, so have an iCloud or computer backup ready before you begin.
6. Try another computer and inspect the hosts file. If error 1604 survives DFU mode, a clean USB chain, updated software, and fresh firmware, the machine itself may be poisoning the restore — borrow a second computer with current iTunes or Finder and run the DFU restore there. On your own machine, check the hosts file for a gs.apple.com redirect, a classic leftover from jailbreak or downgrade tools that sends Apple's signature checks to the wrong place. On Windows, open Notepad as an administrator and open C:\Windows\System32\drivers\etc\hosts; on a Mac, edit /etc/hosts from Terminal. Remove or comment out any line mentioning gs.apple.com, save, restart, and retry the restore.

Did this fix it? Quick checklist

• iPhone in genuine DFU mode: black screen, computer detects the device
• Genuine or certified cable, direct USB port, hubs and docks removed
• iTunes or macOS updated, security software paused, fresh official IPSW downloaded
• Restore completes from DFU mode — no error 1604

If error 1604 survives genuine DFU mode, a clean USB chain, updated software, fresh official firmware, a second computer, and a clean hosts file, the phone's flash storage or logic board may be damaged. Book an Apple Store or authorized service appointment and mention error 1604 so they know the firmware write itself is failing.