iPhone 4

Fourth generation iPhone. Repair is straightforward, but the front glass and LCD must be replaced as a unit. GSM / 16 or 32 GB capacity / Model A1332 / Black and White.

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Why wont my phone restore, keep getting Error 21

My phone wont turn on but will show the apple when I plug it in (either to the wall charger or the computer). It then goes to the plug into itunes screen and when I do it tells me I need to restore the phone. It will get all the way to 'preparing iphone for restore' then will say 'The iPhone "iPhone" could not be restored. An unknown error occurred (21)' I tried to disable my computer security but it did the same thing. Does anyone know what else I could do to fix it? Please help!

Answer this question I have this problem too

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my iPhone does the same thing

by imani

I just had this error, I removed screen, changed battery for another one from a spare phone, connected old screen back on, and YES no more error 21, phone restored fine and working without problem.

by jeffa

ps old battery ribbon connection was damaged.

by jeffa

my phone restore, keep getting Error YES no more error 21, phone restored

by Ankit Gupta

i need help mine does the same thing and it gets me so frusturated ive tried everything to restore it but nothing. please help!!!

by karisma alvarez

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21 Answers

Most Helpful Answer

when the os does not load and all you get is the logo repeatedly booting:

1 pop out the back plate, and then the screw connecting the battery.

2 just unplug the sensor cable and snap it back in.

make sure the iPhone is connected to a power source (though not pertinent if the battery has enough juice)

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I can't pop open the back, I don't have a security screw driver. Can I open up the back with something else? Or is there another way..?

by TaibaAli101

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you don't have to replace battery or even take it out just take off back disconnect the battery(one screw) i don't know if you need to or not but i held home button down for 30 seconds to help fully reset the phone then push the silver connector back on and put phone together. now hold down home button and same time plug it into computer and keep holding home button until phone shows to plug in to iTunes so make sure iTunes is already open before plugging in. then do complete restore and you'll be back in business. trust me i tried for two days i thought i had a paper weight.

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Very well Scott your advice its the solution thanks for share!!

by uio

I can't take off the back, apparently I need a security screwdriver but I don't have one... Is there another way I can get the back off?

by TaibaAli101

Scott 25... I love you... and no you don't have to hold the home button. TaibaAli101, I didn't have a security screwdriver so I used my manicure scissors ;') (P.S.: make sure you also take you sim card tray)

by nadarifki

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I have had this problem for the past 2 days and I finally fixed it. It had nothing to do with the system but the the connection between the battery and the phone had gotten messed up. It kept trying to restore but only ended up with error 21.

My solution: I opened the phone, removed the battery, cleaned out the battery connector and reattached the battery. The phone turned back on and showed the low battery sign. I had done this before and it didn't work. Apparently the problem was I hadn't properly connected them. You need to make sure it's locked on tight so when you close your phone slides on easily. I hope this can help someone else. I was ready to buy a new battery and now I don't have to.

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[http://Here is ]what Apple suggest " Custom firmware restore fail (PwnageTool since 4.1). You have to put your device into the DFU mode and not into recovery mode. Device won't boot correctly an stuck at the Apple logo after the error. Press and hold power and home button until it reboots.

Error when using Sauriks server for a restore with iOS 5.x in the recovery mode at least on a A5 device. " If you need further help, check on here.

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i used to have same problem,apple logo apear and desapear, when was connected to a wall charger or to pc.the problem was the battery it doesnt hold charge then the phone cannot load the os or can not be restored cus phone is no charged replacing the battery solve that issue hope this help to you.

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You saved my girlfriends phone that we thought was dead forever! Turns out it was a compound issue of the battery and an incomplete software update which made it incredibly hard to diagnose. Thanks!

by Nathan

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I faced Error 21 recently and the only way I was able to solve it was by removing the battery and leaving the phone for 2 minutes. I put the battery back, connected the phone to iTunes and the restore worked like a charm.

PS: I am guessing that all the phone needed was a complete hard reset.

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To solve problem with iTunes error "An unknown error occurred (21) " you have to edit hosts file and comment the line with saurik auth servers like this #74.208.10.249 gs.apple.com, or you can use redsn0w restore extra features to force your iphone restore.

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The hosts file may also be blocking the iTunes Store.

If you want to have Windows try to restore the hosts to default, follow the "FixIt" in How do I reset the hosts file back to the default?.

Note: Work systems may put information into the hosts file. Consult whomever is responsible for supporting Windows on your system before resetting the hosts file to default.

If restoring the defaults did not resolve the issue, you can find your hosts file at C:\WINDOWS\SYSTEM32\DRIVERS\ETC .

Select the hosts file. Choose Edit > Copy, and then choose Edit > Paste.

There should now be a duplicate of the hosts file named "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7).

Drag the original hosts file to your Desktop. If Windows needs your permission to continue, click Continue.

Drag the "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) to the Desktop.

Right-click "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) and choose Open. You may be prompted to choose the program you want to use to open this file. Double-click Notepad.

When Notepad opens, choose Edit > Select All, and then choose Edit > Delete.

From the File menu,choose Save. Quit Notepad.

Drag the "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) file from your Desktop back into the original location (given in step 2). If Windows needs your permission to continue, click Continue.

Right-click the "Copy of hosts" (Windows XP) or "hosts -Copy" (Windows Vista/7) file, and choose Rename. Type "hosts" (without quotation marks) and press Enter.

Restart your computer and try connecting to the iTunes Store.

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nizam, i have try all steps that u have said above, but my phone still cant restore from itunes and giving me the same error msg. my phone is down yesterday, if i have no connect usb to pc, i would not get the recovery mode and apple logo. my phone is totally blackout n cant reboot.

by cylosoul backtogarden

can anyone HELP ON THIS ISSUE.. thanks

by cylosoul backtogarden

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whats problem occurrd (21)

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You should ask your own question, try this link http://www.ifixit.com/Answers/Ask/iPhone... and give as much detail as possible.

by oldturkey03

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to fix this problem. is easy 2 things will cause this problem. either charging port or battery or both. replace them and restore problem solved

shakeel the iphone repair guy

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I have a similar problem with my cousins iphone 4 which i offered to look at for her. I have been told that the phone was i great working condition until the phone started to install ios 7 at which point the phone has frozen/crashed, and now wont work at all.

The phone does not show any sign of life while not connected via usb (3 different fully charged batteries have been tested). A Couple of time when pluged into the wall socket the phone has booted up to emergency calls only. When plugged into the computer it boots to the apple logo, and then restarts - sometimes it goes to itunes logo.

Now i have tried several different programs that are supposed to help put the iphone into pwned dfu mode, i have also tried normal dfu mode and restore mode, all of which fail to get past the "Preparing iphone for restore" in itunes, as the phone reboots and goes back to loading either the apple logo and restarting or itunes logo. Then itunes displays error 21. At no point have i seen the phone boot to an Apple Logo with a Loading bar. I have tried on several different computers (win xp/ win 7), different usb cables, and the hosts file never has the 74.***.***.** ip's (i have added them to see if it helped then removed them again). Removing the battery for a while then removing also has not worked.

Programs i have tried include:

ireb -windows

Tiny Umbrella

irecovery

sn0wbreeze

redsn0w

SemiRestore

I have been at this for 1/2 weeks now and have searched google and formus high and low and have not found a solution to this specific problem (none that has worked for me anyway)

Thanks in Advance

Steven

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I have also this problem where when tried to transfer files from iPhone to PC encountered error message which stops my work in between and this situation I would not be able to understand what effective steps required to take so that transfer can be easily. iTunes application also not work and show error which is known as inbuilt application.Lastly I used iPhone transfer tool which works out to be best and helped to transfer files. My problem get easily how to restore iTunes error 21.

Read More:

http://www.iphoneimagerecovery.com

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I know what to do. Under the mainframe is a another frame that you have to fix the spokes if they are bent. This happens due to dropping the iphone. :)

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I tossed my wife's Apple iphone 5 into the Columbia River and bought the cheapest replacement cell phone shown on the AT&T web site. Next time I have a problem will do the same. Saves me hundreds of hours of stress and probably a thousand dollars over a couple years. This is the best solution for these overpriced Chinese poorly constructed devices with constant error issues. Iphone 4s is a much better device. I also can use my ipad sitting on the couch reading email instead of getting in an accident texting or reading while driving.

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Castino; If I'm not mistaken I believe it was the software issue, not the construction you racist pig

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I have had this problem and as a trial swapped battery's with an identical iPhone 4 the phone worked fine then, I then put the old battery into the other phone and the error/ unable to boot up occurred so a new battery will resolve error 21 or other similar boot up problems and is a cheap fix £2.50-£3.50 on e-bay.

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There are many who would like to make transfer of files . Where it is easy and possible to make transfer of files. It is too difficult when try to transfer files with iTunes application. Using tools it is posisble to make transfer of filesEasy to make iPhone 5 Mac transfer].

http://www.iphone5tomactransfer.com

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buy a htc and never get anything with IOS ever again

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Just plugged my I-Phone 5 to Itunes left it there and did a restart on my computer with the phone still plugged in when it started up again I-Tunes opened and did the restore with no error codes. Hope this helps. May not work everytime but worked for me.

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I can't belive that taking of my battery and replugging it would fix that problem thankyou very much

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Replaced with a brand new battery and problem solved

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Clew will be eternally grateful.

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