This error is often related to USB timing. Try changing USB ports, using a different Dock Connector or Lightning Connector to USB cable, and other available USB troubleshooting steps. If you're using a dock, bypass it and connect directly to the white Apple USB dock connector cable. If the issue persists on a known-good computer, the device may need service.
If the issue isn't resolved by USB isolation troubleshooting and another computer isn't available, try these steps to resolve the issue:
- Connect the device to iTunes.
- Confirm that the device is in Recovery Mode. If it's not in Recovery Mode, put it into Recovery Mode.
- Restore and wait for the error.
- When prompted, click OK.
- Close and reopen iTunes while the device remains connected.
- The device should now be recognized in Recovery Mode.
- Try to restore again.
If the steps above don't resolve the issue, try restoring using a known-good USB cable, computer, and network connection.
Follow the steps listed above for Error 1604. You may resolve this error by disabling, deactivating, or uninstalling third-party security, antivirus, and firewall software. Learn more about troubleshooting security software.