Unknown error 21. iTunes errors when restoring, updating and syncing iPhone, iPod Touch and iPad (error codes, causes and solutions). Another option for advanced users

All iPhone users often face the need to update their phone. Updating traditionally occurs through a program on your computer called iTunes. But what to do if you just put your iPhone or iPad on recovery or the update is almost finished, but then suddenly a glitch appears on the screen: “iPhone “iPhone” cannot be restored. Happened Unknown error(21)." What could be the reasons that it was not possible to restore iphone 4s or iPhone 4 and error 21 interfered with us? How can I fix this error myself? We will try to help you with this article.

Error 21 when restoring iPhone 5 and 5s

Of course, Apple produces products that very rarely succumb to the effects of time and breakdowns occur quite less often than in other phones, but alas, there are problems here too, most often found in iPhone 4 and 4s.

What could cause error 21?

The error itself carries with it the concept of a device malfunction. Therefore, first of all, make sure that all interacting devices are working properly.

• Device incompatibility;
• Incorrect connection;
• USB port malfunction;
• Using a non-original charger;
• Phone falling;
• Outdated smartphone updates

How to fix the problem?

Another option for advanced users

Another reason why the problem “iTunes could not restore iPhone 5 error 21” could arise could be a failure of the DFU mode during jailbreak, and this is exactly the way through which the user has the opportunity to have full access to absolutely all files of the smartphone.

To fix this problem you need to use special program redsn0w_win_0.9.15b3, with its help you can restore your phone using DFU mode. To do this, use the following instructions:

1. You need to connect your smartphone to your computer with via USB, and then launch iTunes.
2. The next step is to hold down the Home key and the Power key for about 10 seconds.
3. The next step is to release the Power button, but still hold down the Home key until iTunes detects your iPhone, which is in recovery state.
4. Now the smartphone is in the process of DFU, nothing should be shown on the display.
5. Being in this state, iTunes will still accept the iPhone for data recovery. As soon as you see error 21 again, start restoring IPSW
6. At the end of the process this problem should no longer appear on the screen.

If none of these methods could resolve this problem, we advise you to contact the service center. Because the smartphone could be damaged from the slightest fall. It is possible that some internal parts of the smartphone have been damaged or some individual parts have burned out, and without the eyes of an experienced technician, you will not be able to recognize this problem.

Sometimes when restoring, updating and iPhone sync, iPod Touch and iPad, unknown errors occur in iTunes, and it is impossible to perform the necessary actions with the iOS device. In our directory you will find an explanation of the error and possible options its elimination.

Errors that occur during the recovery/updating and synchronization process can be either software or related to hardware problems in the iPhone, iPod Touch and iPad: some can be easily fixed (by restarting the computer or changing the USB port), others require hardware repair.

iTunes errors occur when:

• , iPod Touch and iPad with iTunes;

iTunes Error Classification

1. Communication problems (Network errors)
   iTunes Errors: 17, 1004, 1013, 1638, 3014, 3194, 3000, 3002, 3004, 3013, 3014, 3015, 3194, 3200.
   Notifications may also appear:
   • "While loading software An error has occurred".
   • "The device is not supported for the requested build."

   These errors and warnings appear when problems arise connecting your computer to the server Apple updates or to the device.

2. Problems with security software settings (firewall, antivirus, firewall)
   iTunes Errors: 2, 4, 6, 9, 1000, 1611, 9006, 9807, 9844.
   These errors are caused by your antivirus, Windows Firewall, or firewall blocking the connection to Apple servers.
3. Problems with the device's USB connection
   iTunes Errors: 13, 14, 1600, 1601, 1602, 1603, 1604, 1611, 1643-1650, 2000, 2001, 2002, 2005, 2006, 2009, 4005, 4013, 4014, 4016, "invalid response", repeated request for recovery after its completion.
4. Hardware problems
   iTunes Errors:(-1), 1, 3, 11, 12, 13, 14, 16, 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 53, 56, 1002, 1004 , 1011, 1012, 1014, 1667 or 1669.
   Occurs due to hardware malfunctions with the iPhone, iPad and iPod Touch: with the modem, with Wi-Fi module, power connector, battery and so on.

Standard troubleshooting steps in iTunes

You can fix most errors in iTunes yourself:

1. Remove or terminate programs on your computer that may be blocking iTunes from connecting to the Apple update server.
2. Disable security software while restoring or updating iPhone and iPad.
3. Use original USB cable to connect iOS devices to your computer. Otherwise it is possible. Try replacing it.
4. . On desktop computer you should use the USB ports located on motherboard. TO USB ports on the multimedia keyboard, USB hub, or front panel system unit It is not recommended to connect an iPhone or iPad - errors may occur when connecting the device.
5. Completely remove iTunes and all its components using “uninstallers”, Uninstall Tool (for Windows), for example. Then install the latest version of the program.
6. Restore/update iPhone/iPad on another Windows computer or Mac.

The table deciphers all known iTunes error codes when restoring, updating, synchronizing and downloading content from iTunes Store and possible options for eliminating them are given.

iTunes Error Guide and How to Fix Them

Apple products are renowned for their reliability, but errors often occur when using iTunes. Probably every Apple gadget user has encountered this at least once. Errors can occur due to a system failure or hardware failure. iTunes error 21 is a hardware issue.

You decided to update the device system and encountered error 21. How can it manifest itself? An error message appears and the iTunes working window closes, after which it will be impossible to work in the program. After the error appeared, the computer turned off. You've received a notification that says "iTunes Error 21." The operating system on your PC runs slow when you issue commands via the mouse or when typing on the keyboard. At times the PC freezes for 3-4 seconds.

Such a failure can generate alerts not only when working in iTunes itself, but also when using components associated with it. When the PC shuts down or when it turns on, failure alerts may also appear 21. By tracking the occurrence of a failure in time, you can easily fix the problem.

Causes

Such a failure may occur due to complete installation components of the iTunes program or if these files are damaged. It can occur when the registry, which is responsible for the iTunes program, is damaged. This can happen due to the installation or removal of software that works with the program.

System files or programs have been damaged by malware or viruses. Files necessary for the proper functioning of iTunes were deleted (intentionally or accidentally) by another program. The most common cause of the error is updating a jailbroken device.

How to resolve Error 21

If you need to update a jailbroken device, use recovery via DFU mode using the Redsn0w program. Redsn0w allows you to restore any gadget from any condition. In order to resolve the failure, enter the device into DFU mode by simultaneously pressing and holding the “Home” and “Power” buttons for 10 seconds. After this, stop pressing “Power” while continuing to press “Home” until a message about emergency recovery of the gadget appears in the iTunes window.

In this case, the device display should be without images. Wait for another message “The iDevice “iDevice” could not be restored...” to appear and perform an IPSW restore. Other methods are aimed at eliminating failures in gadgets that have not been jailbroken.

Updating or installing iTunes

Check if there are updates for the program and update it to the latest current version. If this doesn't help, try completely uninstalling and reinstalling it. Keep in mind that uninstalling may not remove all program components. Therefore, remove it using special utility For complete removal. Only after this install iTunes again.

Turning off the antivirus

Virus tracking software can take program actions such as malicious activity and as a result, stop its operation by means of blocking. In order to avoid such situations, you can turn off the antivirus program while working in iTunes or eliminate failures by disabling the antivirus program after they appear.

In the future, you can add iTunes to the list of exceptions. As a result, the antivirus program will not block its activities. You can do this in the settings. Provided that this function already has activity, you need to disable network scanning.

USB cable

Failures may be caused by the use of non-original components or those that are damaged. Replace the non-original cable with an original one. If you use the supplied cable, check its integrity. Don’t neglect this little detail; using good components can extend the life of your devices and eliminate such failures.

OS update

In order to update Windows system 10 Press two keys “Win” and “I”. This combination will open the options window. Here you need to open the “update and security” section. A work area will open in front of you, where there is a “check for updates” button. Click it. If updates are found, install them.

When using an earlier Windows versions open the "control panel". Here click on "Center" Windows updates» and check. If updates are found, install them.

DFU mode

This mode is for disaster recovery. It works at the hardware level, bypassing operating system. Turn off the device completely and after a couple of minutes connect it to the PC via USB cable. Open iTunes. To enter the gadget into DFU mode, you need to hold down the “Power” button for three seconds and then also hold down the “Home” key. Keep them clamped for 10 seconds. After this time, stop pressing the “Power” button, but hold down “Home” until a notification appears in iTunes that the gadget is in emergency recovery mode. Click on the “restore” button.

Removing garbage

As you use your PC over time, it accumulates a lot of unnecessary information. It can slow down the OS and cause error 21. This occurs due to conflicts between files or when the computer is under heavy load. HDD. You can remove garbage using the Cleanmgr utility. It is built into the system, but has a number of disadvantages. For more complete cleaning It's better to use WinSweeper.

To activate the process, click “start”. Then enter "command" in the search bar. Now hold down the Shift and CTRL keys and click Enter. In the access dialog, click “yes”. A blinking cursor indicates an open black box. Type "cleanmgr" " and click Enter. In the dialog box, check the boxes in the places where you want to clean. Pressing “ok” will start the cleaning process.

You can also restore registry entries. But you shouldn’t do this yourself if you are not an expert in this matter. It is better to contact a person qualified in this field with this question, otherwise you may damage your PC and destroy it. If the above methods do not bring results, go to repair center to diagnose the device. Hardware repair may be required.

Specially designed by Apple for working with devices on the iOS platform, provides Apple owners with synchronization of the device with the computer, comfortable work with content and a lot of others functionality, including firmware recovery. The procedure performed using iTunes is easy to implement, but during the process unexpected problems may arise that interrupt the action. Using notifications with error codes, the program informs users about software failures or hardware problems. iTunes Error 21 may occur when updating or restoring iPhone firmware different versions. Messages about program failures appear for various reasons. Error 21 most often indicates mechanical damage to the device resulting from malfunctions of the modem, device battery, internal boards and other components, but it can also appear as a result of software failures during the jailbreak process. Another reason is often a low battery charge or failure.

Options to resolve error 21 in iTunes.

Despite the fact that this failure is often caused by microdamage resulting from an impact or fall, as well as other hardware malfunctions, there are also software solutions, with the help of which the user can cope with the problem independently.

Method 1: Update iTunes

A universal method, which often allows you to get rid of most application failures when updating or restoring an iPhone 4s and other Apple devices, in some cases also eliminates error 21. If the computer does not have the latest version of iTunes, then after updating and restarting the PC, the problem may be resolved.

Method 2: Replacing the USB cable

Sometimes error 21 can be caused by cable damage or the use of a non-original cord. But even if original equipment is used, it is necessary to inspect it for kinks, twists, oxidation and other minor defects. The correct interaction of the device with the computer largely depends on the integrity of the cable, so if any damage is found, it should be replaced with a working original cord.

Method 3. DFU mode

By activating the DFU emergency mode, you can often get rid of many failures that occur during the update and recovery process, including error code 21. For iPhone 4s and other versions, the procedure follows a similar principle. Before entering the device into DFU mode, you should turn it off completely, and then connect it to the computer using the original USB cable. Next we carry out the following actions:

• Press the “Power” button and hold it for 3 seconds;
• Without releasing the top power button, also press and hold “Home” for 10 seconds;
• after this time, release only the “Power” button, while continuing to hold the “Home” button until iTunes detects the device in DFU mode;
• After the manipulations have been carried out, the program will offer to perform the only action - restoring the iPhone. Next you need to follow the instructions on the monitor.

Method 4. Disabling the antivirus

Some antivirus programs, firewalls and other system defenders can block iTunes processes, perceiving them as virus threats, as a result of which the error that appears prevents the continuation of the procedure. You can pause the antivirus while the firmware is being restored, and after restarting the application, see if error 21 occurs again. If the problem is resolved, you need to add iTunes to the antivirus exclusion list, and also cancel network scanning.

Method 5: Windows Update

In rare cases, updating system components helps, for which you need to go to the Windows update and security settings and search for available updates. If they are found, it is worth installing.

Method 6: Fully charge the device's battery

When the source of the problem is the battery of an Apple device, the method of fully charging the battery often helps. Once the battery has been charged to 100%, you can try the update or restore procedure again.

Method 7: Restoring Registry Files

Restoring registry entries often helps in the fight against iTunes errors if files were damaged by viruses or accidentally deleted by conflicting programs. Automatic correction The WinThruster tool from Microsoft. The program scans and then replaces damaged files with “healthy” ones. Manually adjusting the registry is possible only if you have special skills. Self-fix Without certain knowledge, it can significantly disrupt the operation of the system.

Method 8. Hardware solution

If none of the above methods lead to the elimination of error 21 in iTunes, most likely the problem lies in internal damage to the device. Service diagnostics will help you accurately identify hardware faults. It may be necessary to replace the battery, power controller or lower cable and it is better to entrust the matter to a specialist.

You should not solder or change elements yourself without having the appropriate skills, because one wrong action can only aggravate the situation and lead to irreparable consequences in the form of the final failure of the iPhone.

Most owners mobile technology, including such as iPhone, are well aware and able to perform the recovery and flashing procedure. Unfortunately, sometimes this process ends with the occurrence of another failure. For example, this could be error 21 when iPhone recovery.

I would like to immediately note that it is not always possible to correct such a problem. Unfortunately, sometimes error 21 occurs not due to a software failure, but due to a hardware failure. Naturally, in this case you will only need the help of a good specialist.

It is clear that you should contact a specialist only after you have failed to solve the problem yourself using the methods suggested below.

An attempt to solve the problem using software methods

So, if an unknown error occurs on your mobile phone, you should diagnose it. If, when you try to connect your phone to a computer or connect a charging cable, it first starts showing the Apple icon, and then, literally three seconds later, the iTunes logo and cord, then this is clearly a problem with code 21. This statement is confirmed by the black screen that appears instantly after disconnecting cable.

So, if you were unable to restore your iPhone 4s precisely because of such a problem, then it is recommended to try the following method:

You need to act in a similar way when restoring an iPhone 5.

Unfortunately, this method does not always lead to the desired result. In this case, you should do the following:

If there is no result, then, unfortunately, the problem is a hardware failure.

Hardware solution to this problem

It’s clear that you really don’t want to take your phone to the service center. Usually they charge a lot of money for repairs. Therefore, if you have some experience working with electronics, you can try to carry out the following checks:

If actions at home do not bring results, then, as much as you don’t want to, you will have to take it to the workshop. In this case, there is one recommendation - try to get around as many of these as possible. service centers. Sometimes this can lead to real cost savings. In one place they will quote one price, in another - two or three times lower!