Error 21 Custom Firmware 4.2.1
Jailbreak Developers iPhone Dev Team Saurik MuscleNerd Planetbeing Comex Pod2G P0sixNinja i0n1c iH8Sn0w GeoHot NotCom Jailbreak Guides iPhone Jailbreak Tutorials Jailbreak iPod Touch Jailbreaking Explained Cydia Jailbreak Software Sn0wbreeze Absinthe Blackra1n LimeRa1n JailbreakM Redsn0w Greenpois0n PwnageTool Seas0nPass iPhone Unlock Unlock iPhone Unlock iPhone 3Gs Unlock iPhone 4 Unlock iPhone 4s Ultrasn0w News IOS Wiki Fix iTunes Error 21 During Custom IPSW Restore [How-To Guide]By Ben Johnson last updated June 27, 2014 Share on Twitter Share on Google+ Share on Facebook Share on LinkedIn Jailbreaking your iPhone, iPod Touch or iPod using custom IPSW made by PwnageTool or Sn0wbreeze requires a full firmware restore using iTunes. During the restore process, if you encounter Error 21, it means that you are trying to restore custom IPSW using the recovery mode. To fix this issue, you must put your iDevice into DFU mode.DFU or Device Firmware Upgrade mode allows all iDevices to be restored from any state. The actual difference between recovery and DFU mode is that when you put your iDevice into DFU mode, it do not loads iBoot automatically. When you put your iPhone in recovery mode, it loads iBoot which makes sure that the firmware you are trying to restore is greater or equal to the current firmware.To fix iTunes error 21, you must put your iDevice into DFU mode using the following instructions:Connect your iDevice to your PC or Mac via USB cable and launch iTunes.Hold down the Home+Power button for 10 seconds.After 10 seconds, release the Power button but keep holding the Home button until iTunes detect your iPhone in recovery mode.Once your iDevice is in DFU mode, you should see nothing on its screen. It should be completely blank.Even if your iDevice is in DFU mode, iTunes will detect it as a recovery mode device and will display a message as shown in the above screenshot. As soon as you see the above message, restore custom IPSW and hopefully this time you will not get iTunes
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Using iREB Posted by iPhoneHacks on Feb 22, 2011 | Comments (42) If you hit a 1604, 1603, 1602, 1601, 1600 error while trying to restore your iPhone with a custom http://www.iphonehacks.com/2011/02/how-to-fix-1604-1603-1602-1601-1600-error-while-restoring-custom-ios-4-2-1-ipsw-firmware-file-using-ireb.html iOS 4.2.1 firmware file created using Sn0wbreeze 2.2 for Windows or PwnageTool 4.2 for Mac then there is a way to bypass the error. iH8sn0w, developer of Sn0wbreeze has released a new version of iREB tool, which is compatible with iOS 4.2.1. iREB is a tool that will put your device into a pwned state so that you can upload custom firmware to it. iREB RC3 supports the following iOS devices: iPhone error 21 2G, iPhone 3G, iPhone 3G[S] (old & new bootrom), iPhone 4 iPod Touch 2G (MB & MC), iPod Touch 3G, iPod Touch 4G iPad Apple TV 2 iREB is currently available only for Windows users. Before we start please note that that jailbreaking your iOS device may void its warranty and hence proceed with caution and at your own risk. You can follow these simple step-by-step guide to bypass the 1604, 1603, 1602, error 21 custom 1601, 1600 errors: Download the latest version of iREB from iH8sn0w Start iTunes (iREB needs iTunes 10 or above, it’s a good idea to use the latest version of iTunes – iTunes 10.1.2 as of now) Put your iOS device in DFU mode by following these steps: iPhone/iPad/iPod Touch Connect your iPhone/iPad/iPod Touch to your computer Turn it off Hold power and home together for 10 seconds (exactly). Release power but keep holding home until the computers beeps as a USB device is recognized A few seconds later iTunes should detect your iOS device Apple TV 2 Connect your Apple TV 2 with your Computer via microUSB Now reboot your Apple TV by holding down Menu + Down buttons together for around 6 seconds After reboot, immediately hold Menu + Play until you see the message in iTunes saying that Apple TV in recovery mode is detected Now close iTunes and launch the iREB tool that you had downloaded earlier Click on the relevant device from the iREB screen and wait for few seconds until you get a white or red screen on your iOS device Now start iTunes again and select your iOS device from the left hand side side bar While on the iTunes window, hold the Shift key and click on the ‘RestoreR