Best Fixes For iPhone Error 21

Most of the iPhone users encounter certain issues with their devices. Technical errors might occur for no apparent reason. iPhone error 21 is one such pretty common error that a large number of iPhone users often come across. When you are trying to update, restore or download with iTunes, you may find a pop-up message saying ‘The iPhone could not be restored’ and all of a sudden an unknown error code (21)  appears. This error code can occur due to hardware issues. Furthermore, there can be a communication failure between the servers and your device. If you also encounter iPhone error 21 then take it easy! As you are not alone many iPhone users also struggling with the same error message.

Here, in this article, we have provided a couple of proven methods in order to fix this issue. Hence, keep reading for a hassle-free experience with your iOS device.

What is iPhone Error 21 in Detail?

While updating or restoring, you may often face iPhone error code 21. The most prominent indication is the iPhone error 21 notification box. In such situations, the programs or application suddenly crashes. Moreover, your Apple device runs sluggishly or even tends to be unresponsive. When you get stuck with the error 21 messages, there is something wrong with your iOS device, iTunes or hardware. In most cases, while downloading the restore files (.ipsw) iTunes blocked from authentication and as a result error 21 iphone 5 issue occurs. Sometimes, malware or virus attacks also create some minor to major issues. Thus, you should determine all the possibilities of why the error code arises.

Generic Reasons Behind iPhone Error Code 21

Runtime issues such as error code 21 can be caused due to multiple factors. Thus, you need to troubleshoot each and every factor to prevent it from recurring. So, take a look below to determine the likely reasons.

  1. There can be a connectivity issue between your iOS device and servers.
  2. Besides, incomplete or corrupted installation of iTunes can also create this kind of error code.
  3. Apart from these, viruses or malware can also play a vital role.
  4. Another program maliciously or unknowingly deleted iTunes-related files is also responsible for this issue.
  5. Also, the issue can be with the hardware.
  6. Moreover, if you use an unreliable device, network or USB cable you might encounter iPhone error code 21.
  7. Furthermore, outdated or corrupted iTunes software can also be responsible for this error.

These are the most common factors for which this kind of error code can occur. Now, let’s move on to the troubleshooting section.

Bypass iPhone Error 21 In No Time

There are a number of ways for iphone 4 error 21 to fix. But, here in this post, we have enlisted some easy hacks to troubleshoot this error in no time. Hence, you don’t need to try all of the methods, until you find the one that actually works for you. Get the most suitable one and let us know which one was the appropriate one.

Solution 1: Restart iTunes

Before running iTunes, you need to check that you are using a reliable device, network or USB cable. In most of the cases, restarting iTunes can take care of this kind of temporary error code. To do so, simply disconnect your iPhone from your PC and then close iTunes. Once you are done, run it again and reconnect it with your PC once again.

Once you perform this action, take an attempt to restore or update your iOS device. If you still get the same error code then you need to move on to the next solution.

Solution 2: Update iTunes

Moreover, outdated iTunes can be responsible for the iPhone error code 21. Thus, you should keep your iTunes up-to-date with the latest version. To do so, from the menu bar simply select iTunes. Now, click on the Help. Then, in order to download and install the latest iTunes, look for and select the ‘Check For Update’ option. In this way, you can easily resolve the error code 21.

Solution 3: Disable Security Software

Occasionally, antivirus software can interrupt the connection between the Apple server and the iOS device. Hence, if you have any third-party security program then you should temporarily disable the security software. After disabling it, if you still get stuck with the same error message then you require to uninstall it.

Solution 4: Unplug Unnecessary USB Devices

Primarily, you need to be sure that you have connected your iOS only with your PC. If you use any external storage drive then it might conflict and result in iPhone error 21. Thus, we recommend unplugging all the external USB devices.

Solution 5: Remove/Replace Battery

Poor battery life may lead to iPhone error code 21 in iTunes. Thus, you need to turn off your iOS device and remove its battery. Then, leave it for about 15-20 minutes. After that, reconnect the battery and turn it on, then check whether the id the problem is fixed.

Solution 6: Inspect The Host File

In most cases, the host file blocks iTunes from updating or restoring. In such situations, you need to inspect the host file. To do so, navigate to the Application and then select the Utility option. Now,  click on the Terminal. Now, in the search box, simply enter the command “sudo nano /private/etc/hosts” then scroll down and delete the line immediately.

Solution 7: Check Sensor Cable

Most of the users always ignore the value or the iPhone sensor cable.  If the sensor cable is not properly attached then it may cause several iPhone issues and even result in several error codes. So, we recommend checking the sensor cable. To do so, you need to turn off your iOS device and unscrew the battery and pull it out. Then, clean it properly and set it again.

Alternate Way: Resolve iPhone Error 21 Via Recovery Mode

If none of the methods work for you, this method will surely work for you. Via recovery mode, you can easily fix the error code 21. To do that, follow the below instructions:

Step 1: Put Your iOS Device Into DFU Mode

  • Firstly, press the Power button for about 10 seconds.
  • Then, press and hold the Power and Home button for about 10 seconds.
  • While holding down the home button for 10 seconds more, release the Power button.
  • Now, you will be asked to connect to the iTunes screen.

Step 2: Connect To iTunes

  • Simply connect your iPhone your PC and access iTunes.

Step 3: Restore iTunes

  • In iTunes, simply open the Summary tab and then select the Restore button.
  • When done, your system is going to restart.
  • Once it restarts, it will ask you to Slide to set up.
  • Now, simply follow the onscreen instructions to finish the process.

Bottom Line

These are some different hacks by which you can definitely resolve the iPhone error code 21.

You can let us know which method works the best for you!

Nathaniel Villa
Nathaniel Villa