How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

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These are instructions on how to jailbreak your iPhone 4 on the 4.2.1 firmware using RedSn0w for Windows. The Mac version of this tutorial is here.

You will only be able to perform a tethered jailbreak at this time. This means you will need Redsn0w's assistance to boot into your jailbroken device. If you want to jailbreak a lower firmware version you can find the appropriate tutorial here.

Make sure not to update to iOS 4.2.1 if you need an unlock as one is not yet available!

Step One
Create a folder on your desktop called Pwnage

Download RedSn0w from here and place it in the Pwnage folder. Likewise, download the latest 4.2.1 firmware from below and place it in the same folder.

4.2.1 (4): iPhone3,1_4.2.1_8C148_Restore.ipsw

Extract the redsn0w executable from the RedSn0w zip file into the same folder.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Two
Connect your iPhone to the computer and launch iTunes.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Select your iPhone from the list of devices on the left. Now hold down Shift and click the Restore button. Restore is preferred as it won't create any wasted space on your iPhone.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Navigate to the Pwnage folder on your desktop and select the 4.2.1 firmware ipsw. Click the Choose button to continue.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Three
Once iTunes has finished updating your iPhone to the desired firmware open the Pwnage folder on your desktop and launch the redsn0w application from the redsn0w folder we extracted earlier.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Four
Once RedSn0w opens click the Browse button
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Five
Select the 4.2.1 firmware ipsw we placed in the Pwnage folder on our desktop then click Open.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Six
Once the firmware has been verified click the Next button to continue.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Seven
RedSn0w will now prepare the jailbreak data
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Eight
From this window you can select the jailbreak options you would like.

Make sure Cydia is selected and click the Next button to continue.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Nine
Please plug your iPhone into the computer and make sure its OFF then click the Next button
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Ten
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode here
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Hold down both the Home button and the Power button for 10 seconds.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Release the Power button and continue holding the Home button until RedSn0w detects the device.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Eleven
Your iPhone will now reboot
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Twelve
RedSn0w will then begin uploading the new RAM Disk and Kernel.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

Step Thirteen
Once this is complete you will be notified that RedSn0w is done. Click the Finish button. When your iPhone finishes rebooting (5 minutes or so) it will be jailbroken with Cydia on the SpringBoard.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]


IMPORTANT:
To use Redsn0w to help you boot back into your jailbroken device simply select Just boot tethered right now from the options window and click Next.
How to Jailbreak Your iPhone 4 Using RedSn0w (Windows) [4.2.1]

*As usual a big thanks to the iPhone Dev-Team for their hard work and contribution to the iPhone community.

Mostafa - February 25, 2011 at 5:12pm
Jalbreak process is done succesfully but the iphone is not starting up.it just hangs when i turn it on...PLZ Help
mo - February 25, 2011 at 5:23pm
why you using redsn0w use GreenPois0n alot better and easyer too.
pjaffar - February 10, 2011 at 1:51pm
I download the iOS4.2.1 from the link above and when i try to update my iphone4 to the new iOS i keep gettin the same error 1001 1002 1003 1004 error message. someone can help me fix it ?
Oskar - February 4, 2011 at 3:58am
Hello! I was succesufull jailbreak my iphone 4 (4.2.1) yesterday. But my problem is that I can not get any service from any operator. Can anybody help me?
Bill Carney - February 3, 2011 at 2:04pm
Need help, JB freezes on Uploading ramdisk
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