What is iPhone (iTunes) error 4000

It is a popular error that prevents users from updating their iOS devices. The message interrupting update success usually appears like this – “The iPhone Could not be Updated. An Unknown Error Occurred (4000)” and does not offer any list of solutions. As a rule, the reason why users are unable to perform a successful iPhone update in iTunes is because there is something that blocks proper syncing between the two. It is, in other words, a connection issue that hinders your device and iTunes from working together in order. Very often such connectivity problems are caused by third-party anti-malware software, outdated operating system or iTunes, or even hilarious bugs related to insufficient battery level and locked screen of a device. The 4000 error became a subject of wide discussion in 2021 where most of the reports were centered around iPhone XR while updating from iOS 13.5 to iOS 14.1. However, not excluded that the same issue may occur on other iPhone models and iOS versions as well. If you are also into a struggle of fixing the 4000 error, feel free to follow our tutorial below and try each solution presented. Chances are you will find the one that sorts out the issue.

Download repair tool

Sometimes resolving the errors is out of our control and possibilities. This is where third-party tools are more than welcome to contribute and carry all the difficulties away. If you are facing error 2009 or similar issues, but fail to benefit from any of the manual steps below, try using Tenorshare ReiBoot – a great recovery tool designed for resolving errors like that. Get to know how one can use it to address the errors and restore or update an IOS device successfully on their website.

Download iOS Repair Tool
  1. Download and install ReiBoot for either Mac or Windows.
  2. Once done, open the app and plug your device into the computer.
  3. The program should recognize your device and offer a couple of options.
  4. Choose Standard if you simply want to update your device or Deep repair if you want to fully restore it.
  5. Then, download the firmware found by the app for your smartphone by clicking Download.
  6. Once the process is finished, click Repair now to start resolving the problems.
  7. Standard is meant to search for basic issues and bugs to address them without wiping out your data.

    Deep repair will reset your device to factory settings and delete the entire data stored on it.

  8. Wait until the app finishes its repair and restores your device. It will take about 15 minutes to end.

1. Charge your device over 50% and make sure it is unlocked

We recommend you start with the easiest method on our list. As said, the appearance of error 4000 can be a bug coming from a low battery charge and a locked device screen. Thus, make sure these conditions are met and try to update your device via iTunes again. If this does not work, move on to other solutions discussed further below.

2. Ensure your iTunes and macOS are up-to-date

Using old macOS versions may hint that the error 4000 is related to outdated software. This means it may no longer endorse the same quality of certain features as it was before. Our advice is to check your macOS for available updates and install them if any. We would also advise you to check updates for iTunes as it could be outdated as well. Here is a quick instruction on how you can do this:

To install updates for macOS:

  1. Go to Apple menu in the top left corner of your screen and choose System Preferences.
  2. Then, click Software update and choose Update Now to install the latest update available for your current version.
  3. If you don’t see this button, this means your system is already up-to-date.

Usually, other apps like iTunes get updated along with installing the latest macOS version. However, it is still worth double-checking.

To install updates for iTunes:

  1. Open App Store from the dock on your screen.
  2. Move to Updates on top of the window or left pane and search for iTunes from the list.
  3. If there are any updates available, you will be able to click on Install to get them.

Otherwise, your iTunes service is up-to-date. If you installed iTunes on Windows from Microsoft Store, do a similar procedure there.

3. Disable third-party security software

Reports are being made that users who have third-party antivirus installed and running on Mac may be subject to incompatibility problems while trying to use iTunes for device updating. Thereby, if there is some anti-malware software operating aside from the original Apple security, try turning it off and updating your device again. This could be one of the reasons why error 4000 occurs. In case disabling third-party antivirus does not help or there is simply no third-party software you can switch off, maybe the problem is with your Internet connection. Go ahead and:

  1. Restart the router plus computer and reconnect to your wireless network again.
  2. If you are using a wireless Internet connection, try to connect an Ethernet cable directly to your computer (if there is one available). This should also help you resolve the problem.
  3. You can also find another network and try to use it instead.

4. Make sure you have free memory on your iPhone

One of the biggest fundamentals allowing a device to update is available memory. Each update requires space to be downloaded and installed. If there is not enough free memory on a device for the necessary update, then it has a chance to run into a problem like error 4000. Thus, make sure you check your iPhone (or other IOS device) internal storage for at least a couple of gigabytes. Here is how:

  1. Go to Settings and navigate to General.
  2. Then find and choose [Device] Storage.

From there, you will be able to see how much memory is left. If there is not a lot of it left, and you see barely any free space, then this can be the reason why you are facing the already specified error. Empty some space by deleting or transferring unnecessary files to another storage.

5. Update your iPhone through Settings

If you do not pursue any specific goal while using iTunes and simply want to update your device, then you can also do it via Settings on iPhone itself. You can check availability of new updates by following these steps below:

  1. Open Settings and navigate to General.
  2. From there, find and open Software Update.
  3. If any new updates are pending, you will be able to click on Download and Install.

6. Check your USB cable

When updating a device through iTunes, there is a chance the connection cable is weak due to a damaged or badly connected cable. Try to look over its physical appearance for visible damage and replug it again. Make sure you plug the cable into native PC or Mac USB ports. Avoid using USB hubs and other external devices. If the problem persists, try using a different cable compatible with your iOS device. The same problem could be with your USB port on Mac or PC itself, so make sure you check it as well. If the cable and USB port seem fine, but you continue being struck by the error, move your eyes over to our final recommendation below.

7. Try using another computer

If error 4000 has not yet been sorted out using the methods above, try to borrow a Mac from your friend or other family members to update the problematic device. This method is worth giving a shot since you never know what is the problem with the Mac or Windows computer itself. It is also possible your USB port is damaged as mentioned above, which you are unable to see without sufficient experience. Therefore, give it a try using another computer.


Error 4000 is quite similar to other popular problems (error 2009, 53, 14, 9006, 2015, 1110, 3194) that occur while trying to update a device through iTunes. We had these topics covered on our website as well, so if there are any concerns related to them, feel free and use articles dedicated to them. We hope your iPhone has been updated successfully and you are no longer forced to witness the same or similar errors again.

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