How to Fix iTunes Error 1631 When Restoring iPhone

By ErrorFix · Updated October 23, 2026 · 7 min read

What error 1631 means

Error 1631 pops up in iTunes on Windows or Finder on a Mac while you're restoring or updating an iPhone, and its message is unusually blunt for an iTunes error: it asks you to insert a SIM card into the device and try again. Unlike the cryptic "unknown error" codes in the 3000 range, this one tells you exactly what's missing. Part of the restore process checks that a SIM is present in the iPhone, and when that check fails, the whole restore stops.

The check fails for one of two reasons. The obvious one is that there's genuinely no SIM card in the phone — secondhand iPhones, carrier-unlocked devices, and phones sold without a SIM often hit this the first time someone restores them on a computer. The subtler one is that a SIM is in the tray but the iPhone isn't seeing it: a loose or crooked tray, dust in the slot, dirty contacts on the card, or a SIM reader that's on its way out. And then there's the false positive: shaky USB connections and interfering security software can break the restore at exactly the same stage, producing error 1631 even though the SIM is fine.

Because the fix usually costs nothing — just a SIM card you already own — this is one of the friendlier iTunes errors. Work through the steps below in order and the restore typically finishes on the next attempt.

Common causes

• No SIM card installed: the tray is empty — common on secondhand or carrier-unlocked iPhones.
• Poorly seated SIM: the card is crooked, the tray is loose, or dust and dirty contacts stop the reader from seeing it.
• Unreliable USB connection: a cheap cable, a USB hub, or a flaky port drops the connection mid-restore.
• Outdated iTunes or macOS: old restore software mishandles the SIM verification step.
• Security software interference: antivirus or firewall blocks part of the restore's communication with Apple's servers.
• Faulty SIM reader hardware: rare, but possible if the iPhone also fails to detect SIMs in normal use.

How to fix error 1631 — step by step

Follow these in order. Start with the literal fix — a SIM card in the tray — because that's what error 1631 is asking for, then rule out the connection and software causes before suspecting hardware.

1. Insert a valid SIM card. Error 1631's literal fix is a SIM card in the tray: power the iPhone off, push the SIM ejector tool into the tray hole, and seat a working SIM card with the contacts facing down. It doesn't have to be your own active line — any valid SIM, even a carrier's test SIM, works, because iTunes only checks that a SIM exists. Then connect the iPhone and try the restore again.
2. Check the SIM tray and clean the contacts. If a SIM is already in the phone, error 1631 means iTunes isn't seeing it: the tray may be loose, the contacts dirty, or the card seated crookedly. Remove the tray, look for dust or lint in the slot, wipe the SIM's gold contacts gently with a dry microfiber cloth, reseat the card firmly, and push the tray in until it clicks flush with the frame. Try the restore again.
3. Switch to a direct USB cable and port. Error 1631 can appear when the iPhone and computer aren't talking reliably: disconnect any USB hub, dock, or keyboard pass-through and plug the iPhone's cable straight into a USB port on the computer. Use an Apple-certified cable — cheap third-party cables are a classic cause of restore errors — and try a different port if the first one fails. If you have another cable or computer, test with those too.
4. Update iTunes and the computer. An outdated restore stack can mishandle the SIM check and throw error 1631 even with a good SIM inserted. On Windows, open iTunes, click Help, then Check for Updates, and install anything offered; on newer Windows setups use the Apple Devices app from the Microsoft Store instead. On a Mac, the restore runs in Finder, so install pending macOS updates through System Settings, General, Software Update. Restart the computer afterward and retry the restore.
5. Temporarily disable security software. Third-party antivirus and firewall products can silently block the part of the restore that contacts Apple's servers, which makes iTunes stall and report error 1631. Pause real-time protection on the antivirus and make sure the firewall isn't blocking iTunes, Apple Mobile Device Service, or Bonjour. Attempt the restore once with the protection off, then re-enable everything immediately when you're done.
6. Try a different SIM and then contact Apple. If the restore still fails after trying two different valid SIMs, a known-good cable, a direct port, updated software, and disabled security tools, the iPhone's SIM reader hardware may be at fault — especially if the phone also doesn't detect the SIM in normal use. Book an appointment at an Apple Store or authorized service provider, and mention error 1631: it tells them the restore is stalling at the SIM check, which points them straight at the hardware.

Did this fix it? Quick checklist

• A valid SIM card is firmly seated in the tray, contacts clean, tray flush
• The iPhone is plugged directly into the computer with an Apple-certified cable
• iTunes or macOS is updated to the latest version, then the computer restarted
• Antivirus and firewall paused only for the restore attempt
• The restore completes without error 1631 (or a second SIM clears it)

If error 1631 survives two known-good SIMs, a direct cable, updated software, and disabled security tools, the SIM reader itself is the prime suspect. As a last resort, book an appointment at an Apple Store or authorized service provider and mention error 1631 — it tells them the restore is stalling at the SIM check, which is a hardware question, not a software one.