Skip navigation

HT4972: iOS 4: Updating your device to iOS 5 or later

Learn about iOS 4: Updating your device to iOS 5 or later

HT4972 i'm try to restore my iphone is not retoring is say erro (21) is iphone 4

79 Views 1 Reply Latest reply: Nov 28, 2012 10:20 AM by brad805 RSS
tonynguyen6799 Calculating status...
Currently Being Moderated
Nov 28, 2012 10:12 AM

i'm try to retore my iphone 4 si not retore

  • brad805 Level 5 Level 5 (7,285 points)

    Here is Apple discussion on this error 21:


    This error typically occurs when security software interferes with the restore and update process. Follow Troubleshooting security software issues to resolve this issue. In rare cases, these errors may be a hardware issue. If the errors persist on another computer, the device may need service.


    After following Apple advice if still Error 21, I would perform a DFU Mode Restore.


    Here are the steps. Open iTunes on computer. Connect iPhone to computer with USB cable. Hold both Home and Power buttons, after exactly 10 seconds release the Power Button, keep holding the Home button until iTunes recognizes iPhone in Recovery Mode, usually about 20 seconds time. If the iPhone screen is black, blank this is DFU Mode. Click the Restore button of iTunes. DFU Mode can be difficult to enter sometimes, just keep trying. DFU Mode is a black, blank screen with iTunes saying Recovery Mode.


More Like This

  • Retrieving data ...

Bookmarked By (0)


  • This solved my question - 10 points
  • This helped me - 5 points
This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.