How to Fix iTunes Error 21 When Restoring/Updating iPhone?

The iTunes error 21 or iPhone error 21 is a common issue that is faced by users while restoring their iOS devices. Mostly, while updating an iPhone or restoring it, users get this error which inhibits them from moving ahead. Since the error 21 iPhone could be linked to various issues, you might need to walk an extra mile to fix it. Don’t worry, we are here to help you. If your iPhone could not be restored error 21, then simply read this guide and follow our stepwise solutions.

Part 1: Possible causes of iTunes/iPhone error 21

Since iTunes 21 is a runtime error, there could be plenty of reasons for this. From something wrong in the Windows registry to a busy server, the sky is the limit here. The iPhone error 21 usually occurs when iTunes is not able to download the IPSW or is not authenticated to proceed. Here are some other reasons for error 21 iPhone:

  • • The installation of iTunes was not done properly.
  • • Old version of iTunes
  • • The network connection is not stable
  • • A malware or virus attack on the system
  • • Corrupt registry on Windows or iTunes-related tasks
  • • Authentication issue
  • • Overwriting of commands by another program
  • • Busy server

itunes error 21

Part 2: Remove/disable security software to fix iPhone error 21

As stated, the iPhone could not be restored error 21 happens when there is a conflict between iTunes and a security application. If you have installed an anti-virus software on your system, then we recommend deleting it. Simply go to Control Panel > Programs to get a list of all the programs installed on your system. From here, you can remove the security application to resolve iPhone error 21.

uninstall security software to fix itunes error 21

Part 3: Update iTunes to fix iPhone error 21

If you are using an outdated version of iTunes, then it can also cause the error 21 iPhone. Therefore, it is recommended to update your iTunes in a timely manner if you wish to avoid a situation when iPhone could not be restored error 21.

For Windows users

Windows users can just launch iTunes and visit its “Help” section. From here, you can click on the “Check for Updates” button. This will check the available update for iTunes and provide the download option.

update itunes on windows to fix iphone error 21

For Mac users

Instead of Help, you can just click on the iTunes button and select the “Check for Updates” option to upgrade your iTunes version and fix iPhone error 21.

update itunes on mac to fix iphone error 21

Part 4: Remove host file to fix iTunes error 21

This is one of the simplest solutions to fix iTunes error 21. There are times when a conflict in the host files can lead to iPhone could not be restored error 21 situation. To fix this, launch the Explorer on your Windows and browse to Windows > System 32 > Drivers > Etc > Host.

remove hosts file to fix itunes error 21

Remove Host file from here and place it on any other location. Now, restart your system and try to restore your iOS device again.

Part 5: Fix iTunes/iPhone error 21 with dr.fone – Repair

If you don’t want to go through any unwanted hassle while resolving error 21 iPhone, then simply take the assistance of dr.fone - Repair. It is an advanced and sophisticated tool that can help you fix almost every major issue related to your iOS device in seconds. One of the best things about the tool is that it can fix various iOS-related problems without causing any data loss on the device. To resolve iTunes error 21 using dr.fone Repair, follow these steps.

dr.fone - Repair

Fix iPhone system error without data loss.

  • Only fix your iOS to normal, no data loss at all.
  • Fix various iOS system issues, such as iPhone stuck in recovery mode, white Apple logo, black screen, looping on start, etc.
  • Fixes other iPhone error and iTunes errors, such as iTunes error 4013, iPhone error 14, iTunes error 27, iTunes error 9 and more.
  • Works for all models of iPhone, iPad and iPod touch.
  • Fully compatible with the latest iOS 11.
Available on: Windows Mac
3981454 people have downloaded it

1. Install dr.fone - Repair on your computer and launch it whenever you need to fix error 21 iPhone. From the welcome screen, select the “Repair” option.

fix itunes error 21 with dr.fone

2. Connect your iOS device to the system and click on the “Start” button to commence the repairing process.

connect iphone to computer

3. Before you proceed, the interface will display vital information related to your device. After verifying it, click on the “Next” button.

detect iphone

4. Now, you need to boot your device in the DFU mode. For iPhone 7 and later generations, this is done by pressing the Volume Down and Power button simultaneously and gradually releasing the Power button after 10 minutes. Make sure that your phone should be switched off before proceeding.

boot iphone in dfu mode

5. After your device would enter the DFU mode, you need to provide some details related to it as well. Click on the “Download” button to get its firmware update.

verify iphone firmware information

7. Make sure you have a stable internet connection and dr.fone will download the firmware update for your iOS device.

download iphone firmware

8. After completing the download, it will display the following interface. Just click on the “Fix Now” button to resolve error 21 iPhone.

click fix now to fix iphone error 21

9. In no time, your device will be fixed and restarted to the normal mode. Once iTunes error 21 is resolved, you will get the following interface. Now, you can simply disconnect your iOS device safely from the system.

iphone error 21 fixed

Part 6: Restore iPhone in Recovery Mode

As you know, the iPhone error 21 occurs because the iTunes is not able to download the IPSW files. It also happens when users wish to recover their device in the wrong way. Ideally, you should first put your device in the recovery mode and then connect it to the system to restore it. The iPhone could not be restored error 21 can be fixed by following these steps:

1. Firstly, launch an updated version of iTunes on your system. Take a USB or lightning cable and connects it to the system (and not your iPhone).

2. If you are using an iPhone 7 or newer versions, then you need to long press the Volume Down button. While pressing the button, connect your device to the other end of the cable.

boot iphone 7 in recovery mode

3. The same technique is applied to iPhone 6s and older generations. Though, you have to hold the Home button instead of the Volume Down button.

boot iphone 6 in recovery mode

4. Once the cable is connected, you will see iTunes logo on the device’s screen. You can let go of the button now.

5. Soon, iTunes will detect that your device is in the recovery mode and display a prompt. Just agree to it and restore your device without getting error 21 iPhone.

restore iphone in recovery mode to fix iphoe error 21

We are sure that after following these suggestions, you would be able to fix the iTunes error 21. Simply give dr.fone Repair a try and fix iPhone error 21 or any other issue that is related to your device. It is a remarkable tool and will certainly help you save the day on numerous occasions. Go ahead and give it a try and let us know about your experience in the comments below.

They're downloading

dr.fone - Repair (iOS)

dr.fone - Repair (iOS)

Fix various iOS system issues like iPhone black screen, White Apple logo, etc. without any data loss.

dr.fone - Recover (iOS)

dr.fone - Recover (iOS)

World's 1st iOS data recovery software to recover data from iPhone, iTunes/iCloud backups.

Product-related questions? Speak directly to our Support Team >>

Hot Articles
Home > How-to > iPhone Issues > How to Fix iTunes Error 21 When Restoring/Updating iPhone?