How to Fix iTunes Error 29 on iPhone

By ErrorFix · Updated October 23, 2026 · 8 min read

What error 29 means

Error 29 shows up in iTunes on Windows or Finder on a Mac while you're restoring or updating an iPhone. The dialog reads, "The iPhone could not be restored. An unknown error occurred (29)," and it usually appears late in the process — after the software extracts, while the firmware is installing. The phone drops back to the recovery-mode screen, the one showing a computer and a cable, waiting for a restore that actually completes.

That late failure is the signature of this error. Apple groups error 29 with errors 23, 28, 1011, 1012, and 1611 as codes that may indicate a hardware issue with the device — and Apple's official advice adds two telling diagnostics: try the restore on a known-good computer and network, and check whether the IMEI or the Wi-Fi/Bluetooth MAC address is missing or shows a default value, which confirms a hardware fault. But "may indicate" is doing a lot of work here. In the real world, error 29 is famous for one specific scenario: appearing right after someone replaced their iPhone battery.

The reason is the restore's battery check. While iTunes installs the firmware, the phone verifies that the battery is communicating properly — and a third-party replacement battery, or a connector that isn't fully clicked down, can fail that check and abort the whole install. That's why the battery steps sit near the top of this guide. Still, don't start by opening the phone: bad cables, USB hubs, outdated iTunes, and overzealous security software can all produce error 29 too, and those fixes cost nothing. Work through the steps in order — software first, battery second, hardware verdict last.

Common causes

• Recently replaced or third-party battery: a battery the firmware can't verify is the single most common trigger for error 29.
• Loose or misaligned battery connector: a connector that looks attached but isn't fully seated breaks the battery check mid-install.
• Worn or uncertified Lightning cable: damaged data lines can sustain charging but drop the restore connection.
• USB hub, dock, or flaky port: anything between the iPhone and the computer can disturb the long restore transfer.
• Outdated iTunes or Apple Devices app: old restore software misreading newer hardware and throwing a false error 29.
• Conflicting security software: antivirus or firewall programs interrupting the restore's helper processes.

How to fix error 29 — step by step

Follow these in order. The first four steps clear the software side, step five handles the battery — the most likely culprit — and step six delivers the hardware verdict if nothing else works.

1. Unplug everything non-essential and restart. Unplug everything non-essential and restart. Before suspecting hardware, rule out a glitch on the computer side: on Windows, remove every USB device and spare cable except the keyboard, mouse, and the iPhone, then restart the computer and try the restore again. On a Mac, disconnect third-party devices, hubs, displays, and spare cables. A full restart — not sleep, not a quick sign-out — gives the USB controllers and Apple's helper processes a clean slate, and it costs you nothing to try first.
2. Swap in a genuine cable and change USB ports. Swap in a genuine cable and change USB ports. The cable is the most replaced part in restore failures: worn or uncertified Lightning cables can charge the phone while dropping the data connection the restore needs. Use the cable that came with the iPhone or another genuine or Apple-certified cable, seated firmly at both ends. Plug the iPhone directly into a USB port on the computer — never into a keyboard, monitor, dock, or hub — and try a different port than before. On a desktop, the rear ports on the back of the case are the most reliable because they sit directly on the motherboard.
3. Update iTunes or Apple Devices and the computer's software. Update iTunes or Apple Devices and the computer's software. Old restore software can misread newer hardware and throw a false error 29. In classic iTunes on Windows, click Help at the top of the window and choose Check for Updates, then follow the prompts. If you use the modern Apple apps on Windows, open the Microsoft Store, go to Library, and update Apple Devices, the app that handles restores now. On a Mac, restores happen in Finder, so keep macOS current through System Settings, General, Software Update. Restart the computer after updating and attempt the restore again.
4. Temporarily disable security software. Temporarily disable security software. Apple flags conflicting security software as a repeat offender for restore errors: antivirus, firewall, and endpoint-protection programs can interrupt the USB data stream or block the helper processes that manage the firmware install. On Windows, open Windows Security, go to Virus and threat protection, and pause real-time protection while you retry the restore; also check any third-party antivirus and disable it for the attempt. Turn everything back on immediately afterward — this is a diagnostic step, not a permanent change.
5. Check the battery — reseat it or refit the original. Check the battery — reseat it or refit the original. Error 29 is famous for appearing right after a battery replacement, because a loose battery connector or a third-party battery the firmware cannot verify will fail the install. If you recently replaced the battery, open the phone and check that the battery connector is fully seated and clicked down — a connector that looks attached but sits slightly crooked is a classic cause. If the battery came from a third-party seller, try refitting the original battery, even if it only holds a charge briefly: if the restore succeeds with the original battery, the replacement battery is the problem. Charge the phone fully first if the original battery is deeply discharged, and make sure the connector area is clean and undamaged.
6. Try a second computer, then check for hardware damage. Try a second computer, then check for hardware damage. If the same iPhone with a good cable and the original battery still throws error 29, isolate the computer: run the restore on a different computer with a known-good cable and current software. When the restore succeeds there, the phone is fine and the first computer was the problem. If error 29 follows the phone to a second computer, the fault is in the hardware — Apple groups error 29 with 23, 28, 1011, 1012, and 1611 as possible hardware issues. Check Settings, General, About on the phone: if the IMEI or Wi-Fi/Bluetooth MAC address is missing or shows a default value, that confirms a hardware fault. At that point, book an appointment at an Apple Store or authorized service provider and mention error 29 — it tells them exactly which stage of the restore failed.

Did this fix it? Quick checklist

• Only the keyboard, mouse, and iPhone connected, computer fully restarted, genuine cable direct into the computer
• iTunes or Apple Devices updated, and security software disabled only for the restore attempt
• Battery connector fully reseated (or original battery refitted) if the error followed a battery replacement
• The restore completes without error 29 — on this computer or a second one — or a hardware fault is confirmed via missing IMEI/MAC

If error 29 survives a clean USB chain, current software, a reseated original battery, and a second computer, stop troubleshooting the software: the phone's battery connector, charging circuit, or logic board is damaged. Book an appointment at an Apple Store or authorized service provider and tell them error 29 appeared during the firmware install — with the IMEI check already done, they'll know exactly where to look.