A number of iPhone / iPad users have complained about the iTunes error 21 from time to time when trying to restore or update their device in iTunes. If you have encountered error 21 in iTunes and are looking for a way to fix it. In this article, we will show 4 methods that will probably work and fix error 21 or iTunes error 21 when restoring or updating your iPhone / iPad under iOS 12/11/10/9/8.
- Connectivity failure between your device and the servers.
- Download corrupted or incomplete installation of iTunes software.
- Corruption in the Windows registry following a recent software change related to iTunes (installation or uninstallation).
- Virus or malicious program that has corrupted Windows system files or program files associated with iTunes.
- Another program has maliciously or incorrectly deleted files related to iTunes.
- Hardware error.
Runtime errors such as "Error 21" can be caused by various factors. It is therefore important to solve each of the possible causes to prevent them from happening again.
Before trying any of the methods below, it is highly recommended to restart iTunes multiple times and remove unnecessary USB devices from your computer. They might be useful in certain circumstances.
Method 1. Update iTunes
Sometimes older versions of iTunes may contain bugs. If you're still using the old version of iTunes, it's time to get the latest one. You will find below how to get the latest version of iTunes.
- Launch iTunes, go to the menu at the top left, click Help, and then click Check for Updates.
- If you do not have the latest version of iTunes, a message asking you to download the latest version of iTunes appears.
- Click Download Now to get the latest version of iTunes on your computer.
Method 2. Disable Anti-Virus
Sometimes Anti-Virus can block iTunes to download restore files. You can press Ctrl, Alt, and Delete simultaneously, and then select Anti-Virus to terminate their process.
Method 3. Delete the host file
- Go to C: / windows / system 32 / drivers / ect / host.
- Move the host file to the desktop or to a place where you can find them.
- Try to restore your iDevice again.
- After restoring your iDevice, please delete the host file.
Method 4. Restore iDevice by Recovery Mode
Restoring iDevice via DFU (Device Firmware Upgrade) mode allows you to fix iTunes error 21. However, this could result in data loss. Please only use this method if you are running out of solutions.
Step 1. Put iDevice in DFU mode
Hold down the power button for 3 seconds, then hold it down for 15 seconds. Release the power button while holding down the Home button for another 10 seconds.
A message will appear asking you to "connect to the iTunes screen", click OK.
Step 2. Connect your iDevice to the computer via a USB cable, then launch iTunes.
Step 3. Click the Summary tab, and then click Restore. Your iDevice will restart on its own.