Iphone has encountered an unknown error 21. Troubleshooting errors when restoring Iphone

Specially developed by Apple for working with devices on the iOS platform, it 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. Error 21 in iTunes may occur when updating or restoring firmware iPhones of different versions. Messages about program failures appear on various reasons. Error 21 most often indicates mechanical damage devices resulting from malfunctions of the modem, device battery, internal boards and other components, but may 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.

Although this failure often triggered by microdamages subsequent to 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 that often allows you to get rid of most application failures when updating or restoring iPhone 4s and other “Apples”, in some cases it also eliminates error 21. If the computer does not have the most latest version 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 inserting 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 letting go top button power supply, also press “Home” and hold it 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 may 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 update settings and Windows security and search 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. 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.

Upon recovery iPhone iTunes sometimes it produces an unknown error with a number, without correcting which it is impossible to continue working with mobile device. Depending on the number of the problem that prevented you from restoring your iPhone, there are different ways to fix the problem.

Error classification

Service Apple support on special page The website divides failures by numbers into several categories. However, you will not find some codes. For example, there is no number 52 on the support page, because iTunes does not crash with such a code. Error 47 is also not listed, although some users complain that due to a glitch with this number they are unable to restore their iPhone.

If you encounter problem 47, there may be several reasons for its occurrence:

1. Failure of the modem chip.
2. Modem processor failure.
3. Liquid has entered the modem part.

As you can see, error 47 is due to a hardware problem. Therefore, if you encounter error 47 while restoring your iPhone, take your mobile device to service center. Even the master does not immediately determine the exact cause problem number 47 appears, so it’s better not to risk trying to repair it yourself.

Communication errors (1671, 3004, 3014, 3194)

If during recovery iPhone iTunes displays a message with numbers 1671, 3004, 3014, 3194 or 9006, then you are dealing with problems that are preventing your computer from establishing a connection with the Apple server or mobile device. If problems 3004, 3014, 3194, 9006 occur, first try restarting your computer. If this does not help, close applications that are running background, leaving only iTunes. Disable your firewall and antivirus. Since failures with numbers 3004, 3014 3194, 9006 occur due to the inability to establish a connection to the server, disabling the firewall will help remove the firewall.

If these methods do not help get rid of failures 3004, 3014, 3194, 9006, then try the following methods:

The extra entry will end with gs.apple.com. If you find one, delete it immediately and save it hosts file. After hosts edits Failure messages 3004, 3014 3194, 9006 should no longer appear when restoring an iPhone. If problems with numbers 3004, 3014 3194, 9006 appear when restoring iPhone to Mac computer, then open hosts through the terminal using the command “sudo nano /private/etc/hosts”.

If iTunes displays error 3194 when the recovery line is 2/3 full, then most likely you are faced with a hardware problem - damage to the modem or iPhone power module.

If you cannot restore your device due to problems with the modem, contact a service center for help, as you will not be able to fix the problem yourself.

Errors 14 and 4005

Failures with numbers 14 and 4005 when restoring an iPhone usually occur when problems are detected with connecting the device via USB. Error 14 indicates that during the recovery process, iTunes detected a violation of the integrity of the firmware file. Error 4005 usually indicates that there is some problem with the cable or port on the computer.

To fix error 14 or 4005:

• Use the original iPhone cable.
• Connect the device to a different port. Try to use connectors that are on the rear panel system unit, then you will give less chance of errors like 14 and 4005 appearing.
• Connect your iPhone to another computer.

If error 14 or 4005 persists, try putting your phone into DFU mode before restoring. If this does not help resolve failure 14 or 4005, download the firmware manually and select the desired ipsw file by holding down Shift key when you click the "Restore" button.

Errors numbered 14 and 4005 appear when you try to update the firmware by jumping through the version (for example, from iOS 7 directly to iOS 9). To avoid problem 14 or 4005, choose suitable version firmware.

Error 21

Failure number 21 occurs when the device is incorrectly entered into DFU mode. To eliminate the cause of error 21, use programs like redsn0w to transfer the phone to DFU.

Owners of iPhones that have been jailbroken especially frequently encounter crash 21. In addition, failure 21 may occur due to the fact that the battery is not fully charged. Accordingly, to fix problem number 21, you need to put your smartphone on charge.

Many users have heard about the quality of Apple products, however, iTunes is one of those types of programs when working with which almost every user at least once encounters an error in operation. This article will discuss ways to resolve error 21.

Error 21 usually occurs due to hardware problems with the Apple device. Below we will look at the main ways that can help solve the problem at home.

Method 1: Update iTunes

One of the most common reasons occurrence of most errors when working with iTunes - update the program to the latest available version.

All that is required from you is iTunes check for updates. And if available updates are detected, you will need to install them and then restart your computer.

Method 2: Disable antiviruses

Some antivirus and other security programs may mistake some iTunes processes for viral activity, and therefore their work is blocked.

To check for this possibility of causing error 21, you will need to temporarily disable your antivirus, then restart iTunes and check for error 21.

If the error disappears, then the problem really lies in third party programs, blocking iTunes actions. IN in this case you will need to go to your antivirus settings and add iTunes program to the list of exceptions. Additionally, if you have such a function active, you will need to deactivate network scanning.

Method 3: Replace the USB cable

If you are using a non-original or damaged USB cable, then most likely it is the cause of error 21.

The problem is that even those non-original cables, which have been certified by Apple, may sometimes not work correctly with the device. If your cable has kinks, twists, oxidation or any other types of damage, you will also need to replace the cable with a complete and original one.

Method 4: Update Windows

This method rarely helps solve the problem with error 21, but it is listed on the official Apple website, which means it cannot be excluded from the list.

For Windows 10, press the keyboard shortcut Win+I to open the window "Options" , and then go to the section "Update and Security" .

In the window that opens, click on the button "Checking for updates" . If the scan found updates, you will need to install them.

If you have a younger Windows version, you will need to go to the menu “Control Panel” - “Center” Windows updates» and check for additional updates. Install all updates, including optional ones.

Method 5: Recover devices from DFU mode

DFU emergency mode work of gadgets from Apple, which is aimed at troubleshooting problems with the device. In this case, we will try to put the device into DFU mode and then restore it through iTunes.

To do this, completely disconnect your Apple device, and then connect it to your computer with via USB-cable and launch iTunes.

To enter the device into DFU mode, you will need to perform the following combination: hold down the power key and hold for three seconds. After that, without releasing the first key, hold down the “Home” key and hold both keys for 10 seconds. Next, you just have to release the power key, but continue to hold “Home” until your device is detected by iTunes (a window should appear on the screen, as shown in the screenshot below).

After this, you will need to start device recovery by clicking on the appropriate button.

Method 6: Charge your device

If the problem is a problem with the battery of your Apple gadget, then sometimes it helps to solve the problem fully charged devices up to 100%. Once the device is fully charged, try the recovery or update procedure again.

In conclusion. These are the main methods that you can perform at home to solve error 21. If this does not help you, the device most likely needs repair, because Only after diagnosis will a specialist be able to replace faulty element, which is the cause of problems with the device.

All iPhone users We often encounter the need to update our 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

Undoubtedly, Apple company produces products that are very rarely susceptible to exposure and time, and breakdowns occur quite less frequently 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 precisely the way through which the user has the opportunity full access to absolutely all smartphone files.

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

1. You need to connect your smartphone to your computer using 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.

It may be necessary to carry out the recovery procedure for iPhone 4 if the system or individual modules are not operating normally, or if the lock screen password is forgotten. We'll tell you how to save photos and other user information, revive your iPhone and get rid of failures in which the system issues codes 3004, 2009, 16, 4005, 4013, 3194.

Creating a backup

Any iPhone recovery method involves installing new firmware and loss of all personal data on the iPhone. Fortunately, archival copies photo and other important information easy to do. You will need iTunes and a computer:

1. Connect iPhone to computer;
2. When the device is detected, right-click on its icon;
3. IN context menu select the copy command.

You can synchronize your iPhone with any of the free cloud services- this is how the gadget sends every photo taken when connected via Wi-Fi to network storage.

Standard reset method

This is a simple method that in many cases allows you to get rid of glitches when iPhone work. User information and photos are not saved, settings are reset to factory settings. In order not to experience additional difficulties when restoring the firmware, it is better to immediately use the latest one iTunes version, as well as iOS.

Although an application on your computer can download the OS for you during the firmware update, sometimes the iPhone crashes 3194, 3004, 4005, 21, 11, etc. In addition, the iOS version installed automatically will be the latest, which suits everyone not every iPhone owner.

The procedure for flashing the standard firmware of the device is as follows:

The device will go to Recovery Mode and reset the settings to factory settings, the user will be able to return contacts, photos, etc. through the created backup.

Standard update

If you haven’t made any archived saves, your iPhone is crashing, a flashing is required, but you don’t want to lose your personal data, try updating the system rather than restoring it. In this case, iOS will also be reflashed, but the photo and all other information will not be lost. In this case, the chance of fixing bugs is less, and you won’t be able to reset the password.

Starting from 5th iOS versions this update method is available not only through iTunes, but also simply when available Wi-Fi networks. It makes no sense to consider the first method in detail, since it completely repeats the recovery method described above; you just need to click the “Update” button in the 4th step. It's even easier to do this over a Wi-Fi network:

• in the “General” section of the gadget settings, open “Software Update”;
• A line with the latest firmware version will be displayed, click on the bottom line for download and update.

All you have to do is wait for the process to finish. iOS will be reinstalled, password, settings, photos, etc. will be saved.

Fixing errors in Recovery Mode

With Recovery Mode you can solve most problems and reset your password. Recovery is also carried out through iTunes; data, including photos, contacts, etc. are not saved. The flashing technique is similar to that described above, only in Recovery mode the user enters his iPhone independently. Sequencing:

1. Turn off the device.
2. Press and hold Home on your phone, while connecting it with a cable to your computer via iTunes.
3. The appearance of the media player icon and USB cable on the display will indicate that the phone has entered Recovery mode.
4. If iTunes does not load automatically, launch it and make sure that the media player recognizes the connected device - a corresponding notification will appear on the screen.
5. Next, select the iPhone in the same way, hold Shift and click on the restore button.
6. All that remains is to indicate the location of the new firmware, start the process and wait for it to finish, enter Apple password ID and update settings.

Using DFU Mode

Even with simple update firmware, the need to reset a password, etc. It is recommended to do this bypassing the OS through DFU mode, making a backup in advance, saving a photo, downloading the firmware file and then restoring personal data. In this way it is possible to eliminate not only the most severe software problems, reset the password, but also avoid all sorts of failures, for example, with codes 16, 21, 11, 4005, 3194, etc., which often occur when reinstalling the OS using other methods.

The reinstallation sequence in this case is completely the same as described above, except that the iPhone will need to be forced into DFU mode, not Recovery. This is done as follows:

1. Connect your iPhone to your computer and turn it off, or hold down the power and home buttons simultaneously for 10 seconds.
2. After 10 seconds, release the power button while holding down “Home”.
3. Continue to hold it down until the PC displays a message indicating that the gadget has been detected.

Judging by the message, it will be detected in Recovery Mode, however, DFU mode can be recognized by the absence of any image on the display - it should be black or white, depending on the model.

Possible failures during flashing

To reset your password and troubleshoot software problems with Apple gadgets, it is better to use DFU mode. However, many users experience certain difficulties logging into it, so in order to remove the password, they reinstall iOS directly from the system or in Recovery Mode, which sometimes causes an error. The codes may vary - 16, 21, 11, 4005, 4013, 4014, 3194, etc. Let's look below at the reasons for update failures and how you can deal with them.

The appearance of failure codes 4005, 4013 and 4014

Codes 4005, 4013 and 4014 appear mainly after the gadget is disconnected from the PC during the update process, or if the program is interrupted for other reasons during execution. To correct the situation:

• install the latest version of iTunes;
• try using another original USB cable or even a computer;
• force a reboot of the device;
• if the front one was used USB port, engage the rear one.

Often error numbers 4005, 4013 and 4014, along with 16, 21, 11, etc., occur due to faulty iPhone hardware. For example, if the device is dropped, the contacts of the modem chip, compass chip, etc. may be broken. When updating, the phone diagnoses all modules and if it does not find any, it displays a window describing the fault - error 11, 16, 21, 4005, 4013 or 4014. Therefore, if the above methods do not help, the iPhone will have to be taken to a service center, where the technician will have to resolder the problematic chips.

Failure 3004 when updating

Sometimes when reinstalling iOS via iTunes, the process is interrupted by code 3004. There are two main reasons:

• blocking software installation by antivirus, as a result of which iTunes loses the ability to contact the server;
• the work of a firewall that evaluates downloaded information as a threat and also blocks it.

Error 3004 can often be resolved very simply:

1. Disable all security software, and then restart the update mode via iTunes.
2. Sometimes the purpose of the browser Internet Explorer The main solution is to solve the problem with code 3004. This is done in the “Programs” tab of the browser properties.

If you still see error 3004, clean your system of viruses. Malicious code, along with pirated software used in the gadget, can also make it impossible to carry out iOS reinstallation due to failure 3004.

Reinstallation fails due to code 2009

If the connection between the computer and the device is broken, iTunes displays a message that error 2009 has been found and the process is terminated. The problem with the appearance of 2009 is solved in the following ways:

1. Change the cable to another one original apple USB;
2. Connect via another USB port or computer with installed player iTunes;
3. Disconnect all working USB devices from the PC except for the necessary ones - keyboard, mouse and the device being directly flashed.

If error 2009, 4005, etc. is not resolved, the iPhone will have to be serviced.

Malfunctions with codes 11, 16 and 21, etc. do not allow you to reflash the device

If the phone does not reflash and displays errors 11, 16 or 21, there is a high probability of hardware problems. This may be a malfunction of the radio module, a mismatch checksum And serial number device For this reason, previously errors 11, 16 and 21, like 4005, could appear on iPhone 4 and 4S after restoration in China - they were sold under the “like new” or Refurbished brand.

1. Update iTunes, disable third-party security software;
2. Please use another original USB cable;
3. Check the functionality of your PC and network, make a couple more attempts to reinstall iOS using the DFU mode - this way the likelihood of failures 11, 16 and 21 appearing will be minimal.

If all attempts are unsuccessful, the system issues codes 11, 16 and 21, 4005, then the problems will have to be fixed in the service.

Troubleshooting 3194

Error 3194 indicates that the iTunes program cannot receive a response from the firmware when sending a request to sign the firmware. Apple servers. Reasons why code 3194 appears:

• changes to the hosts file, for example, for use when caching Cydia servers;
• Apple does not issue signatures for older firmware, triggering failure 3194.

There are several ways to resolve fault 3194:

1. Update iTunes.
2. Install the TinyUmbrella application on your PC. After launching the utility, open the Advanced tab and uncheck the box next to Set Hosts to Cydia and try to recover again. In this case, iTunes will stop connecting to Cydia instead of Apple's servers and fail with error 3194.
3. Open on your computer system file hosts using Notepad. Delete the line 74.208.105.171 gs.apple.com from the file, save and restart your PC.

One of the proposed options will certainly be able to save you from the occurrence of a failure - error 3194 will disappear, after which you can reflash the phone, enter New Password, return photos and settings.

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