Record the complete restore error, update the computer and Apple software, use a direct USB connection, and retry with a known-good cable. Repeated hardware-related codes or a device that cannot stay connected should go to Apple service.
“The iPhone could not be restored” is not one diagnosis. The error number and the stage where it appeared matter. Take a photo or write down the complete message before closing it; repeated restores without that evidence can erase data without fixing the connection or hardware fault.
Fix the computer side first
Install current macOS or Windows updates and the latest Apple Devices app or iTunes supported by the computer. Restart both computer and iPhone. Connect directly to a built-in USB port with a data-capable cable; remove hubs, keyboard ports, docks, and unrelated USB accessories.
Check that security software, a managed network, or a modified hosts file is not blocking Apple update servers. On a work computer, ask the administrator rather than disabling protections. Make sure the computer has enough free space for the software download.
Retry according to the message
If the phone can start, make a backup before another update or restore. If it cannot start, place it in recovery mode and choose Update before Restore when that option is available. Keep the connection stable until Finder or Apple Devices reports completion.
Network or server messages call for a reliable connection and a later retry. USB communication messages call for another cable, port, or computer. Apple groups some recurring numbered errors with possible hardware issues; do not promise that third-party firmware tools will repair them.
Confirm completion or escalate
A successful operation ends with the setup or Lock Screen and the computer no longer reporting an error. Verify the iOS version, cellular service, charging, and the newest usable backup before deleting any older backup.
If the same code returns on another known-good cable and computer, the phone disconnects whenever it moves, or recovery mode cannot complete, give Apple Support the error number, computer version, app used, cable tests, and whether there was liquid or impact. Never give a repair contact your password or one-time verification code.
Primary sources
Interfaces and policies change. We recheck the steps above against these sources and show the verification date at the top of the guide.