How to Fix iTunes Error 4015 When Restoring iPhone
What error 4015 means
Error 4015 shows up when you restore or update an iPhone through a computer, and iTunes or Finder interrupts the process with the message: The iPhone could not be restored. An unknown error occurred (4015). Despite the vague wording, the failure is a familiar one: 4015 belongs to the same family as the better-known restore errors 4013 and 4014, and it follows the same pattern — the restore starts, communication between the phone and the computer breaks down somewhere in the middle, and the whole process aborts.
That breakdown can happen for a surprisingly ordinary set of reasons. A worn Lightning or USB-C cable, a loose USB hub, an iTunes version that predates your iOS version, or an antivirus program that decides the restore traffic looks suspicious can each stop the process cold. In those cases the phone itself is perfectly fine, and the fix is on the computer side. The scarier possibility is hardware: on phones that have been dropped, repaired, or exposed to water, the same error can point at a failing storage chip or a battery connection problem, which no amount of software troubleshooting will fix.
The trick is telling those two situations apart without wasting a day. Work through the steps below in order, cheapest first. Most 4015 cases clear up in the first three steps. If the error survives a different computer, a different cable, and a DFU restore, that is the signal that the phone itself needs a repair shop — and you will know it for certain rather than guessing.
Common causes
- Faulty or uncertified cable: a worn or third-party cable drops the connection mid-restore.
- USB hub or adapter in the chain: hubs and docks add failure points between the phone and the computer.
- Outdated iTunes or macOS: old updater software cannot talk properly to a newer iOS version.
- Security software interference: antivirus, firewall, or VPN software blocks the restore traffic.
- Corrupted firmware download: a damaged or interrupted iOS download fails verification during the restore.
- Hardware fault: a failing storage chip or battery connection, especially after drops or water exposure.
How to fix error 4015 — step by step
Start with the connection and the software. The heavier tools — recovery mode and DFU — come only after the easy fixes have had their chance.
- Restart the computer and the iPhone, then reconnect with a good cable. Restart the computer completely, force restart the iPhone, and then connect the phone straight into a USB port on the computer with an Apple-certified Lightning or USB-C cable. Skip hubs, docks, and adapters for this attempt — a shaky connection is the single most common trigger for 4015, and a clean restart plus a solid cable rules it out before you touch anything else.
- Update iTunes or macOS to the latest version. Outdated updater software is a known contributing factor for 4015. On Windows, open the Microsoft Store, go to Library, and install updates for the Apple Music and Apple Devices apps — or in classic iTunes, go to Help, then Check for Updates. On a Mac running macOS Catalina or later, updates happen through Finder, so open the Apple menu, go to System Settings, then General, then Software Update. Restart the computer after updating, then retry the restore.
- Temporarily disable security software on the computer. Antivirus programs, firewalls, and VPN software can block the connection between iTunes or Finder and Apple's servers mid-restore, which produces exactly this kind of failure. Turn the security software off just for the restore attempt, keep the computer on a network you trust, and turn the protection back on the moment the restore finishes or fails.
- Try recovery mode and choose Update first. Connect the iPhone to the computer, then enter recovery mode: quickly press Volume Up, press Volume Down, then press and hold the Side button until the recovery screen appears. In iTunes or Finder, choose Update — this reinstalls iOS while trying to keep your data. Only choose Restore if Update fails, because Restore erases the phone completely.
- Try a DFU mode restore if recovery mode fails. DFU mode loads no iOS at all, so it can succeed where a normal restore cannot. With the phone connected to the computer, press Volume Up, press Volume Down, then hold the Side button for 10 seconds, then keep holding the Side button while also holding Volume Down for 5 more seconds, then release the Side button while continuing to hold Volume Down until the computer detects a device in recovery. Click Restore in iTunes or Finder and let it download a fresh copy of iOS. This erases everything, so only use it when you have a backup or have accepted the data loss.
- Try a different computer, cable, and port. If 4015 survives every step above, the problem may sit on the computer side rather than the phone. Borrow a different computer, use a different Apple-certified cable, and plug into a different USB port. If the restore succeeds there, your original computer, cable, or port was the culprit — update its drivers, try another port, or reinstall iTunes or the Apple Devices app.
- Get the hardware checked if the error never goes away. Error 4015 belongs to the same family as 4013 and 4014, and when it persists across computers, cables, and DFU restores, it usually points at a hardware fault — most often the storage chip or the battery connection, especially on a phone that has been dropped or exposed to water. Book an appointment with Apple Support or an authorized repair shop and tell them you have already tried recovery mode and DFU restores.
Did this fix it? Quick checklist
- Computer fully restarted and iTunes or macOS on the latest version
- Apple-certified cable plugged directly into the computer, no hub
- Security software off for the restore attempt, back on afterward
- Recovery-mode Update tried before any Restore or DFU attempt
- The restore completes without 4015 — or the failure is confirmed on a second computer
If 4015 keeps appearing on a second computer with a different cable, stop repeating the same restore — you have already ruled out the software side, and further attempts will not change the answer. Back up what you can, and let Apple Support or an authorized repair shop check the hardware. Bring the full story: which steps you tried, and that the error survived recovery mode and DFU.
Frequently asked questions
What does iPhone error 4015 mean?
It means iTunes or Finder could not finish restoring or updating your iPhone. The process starts, gets partway through, and then aborts with the message: The iPhone could not be restored. An unknown error occurred (4015). It belongs to the same error family as 4013 and 4014.
Will fixing error 4015 delete my photos and data?
The error itself does not delete anything — it only means the restore or update could not complete. But recovery-mode Restore and DFU mode do erase the phone completely, so always choose Update first in recovery mode, and only use Restore or DFU when you have a backup or have accepted losing the data.
Is error 4015 a hardware problem?
Not usually. Most 4015 failures come from a bad cable, an outdated iTunes or macOS version, or security software blocking the restore. It only points to hardware when it keeps happening across different computers, cables, and DFU restores — then the storage chip or battery connection is the likely culprit, and the phone needs a repair shop.
How is error 4015 different from error 4013 or 4014?
They are close cousins in the same restore-error family and share the same fixes: cable, updated software, security software off, recovery mode, then DFU. The number itself does not change the troubleshooting — what matters is whether the error survives every software step, which is what separates a fixable glitch from a hardware fault.
Should I try DFU mode first for error 4015?
No. Work in order: restart and a good cable, updated iTunes or macOS, security software off, then recovery mode with Update. DFU mode is the last resort because it erases the phone and takes the longest, and most 4015 cases are fixed before you ever need it.