iOS 4.2.1 GM Jailbreak with Redsnow 0.9.6 b2 on iPhone 4, 3G, 3GS and iPod

Apple has just released iOS 4.2.1 GM and fortunately it is jailbreakable with the latest Redsnow 0.9.6 b2 which is based on GeoHot’s Limera1n exploit.

Redsnow 0.9.6 can jailbreak iPhone 4, iPhone 3GS, iPhone 3G, iPod Touch 4G, iPod Touch 3G and iPod Touch 2G on iOS 4.2.1. iPad is not yet supported by Redsnow but you can use the PwnageTool to jailbreak iOS 4.2.1 on iPad.

But there is one problem that Apple has changed some private APIs used by Cydia and due to which Cydia crashes when you try to start it. Cydia for iOS 4.2.x is almost ready and the iPhone Dev Team is waiting for the final and public build of iOS 4.2.1 before they release it. As you get the full root access after you jailbreak your idevice, so you can also install the jailbreak apps via SSH.

Here is the step by step guide to jailbreak iOS 4.2.1 on iPhone and iPod Touch version with Redsn0w:

Step 1: Download iOS 4.2.1 GM (links to downloads or download pages are listed at the bottom of this post).

Step 2: Download iOS 4.1 final version.

Step 3: Download Redsnow 0.9.6 b2.

Step 4: Using the iTunes 10.1, update/restore your phone to iOS 4.2.1 GM downloaded in step 1.

Step 5: Start the Redsnow jailbreak tool and open the iOS 4.1 in it to star the jailbreak process. (Please make it sure that you selected the iOS 4.1 IPSW file in this step).

Step 6: Press the Next button after Redsnow identifies the IPSW file successfully.

Step 7: Now check the Install Cydia Option. You can also select any other option if available.

Step 8: Switch off your phone and connect it with the PC before you proceed.

Step 9: Follow the Redsnow on-screen instructions to put the iPhone into DFU mode.

Step 10: Wait a few seconds for redsn0w to do its thing. After you receive the DONE message, close Redsn0w and enjoy jailbroken iPhone on iOS 4.2.1.


iOS 4.1 Direct Download links:

Note: If you rely on unlock, don’t update you device to iOS 4.2.1 otherwise you’ll lose carrier unlock and there is no unlock available for iOS 4.1 and above yet.

Disclaimer: This guide is for testing and educational purpose only. Use it at your own risk. This site will not be responsible for any type of damage.

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Author: A. Usman

Loves new tech, especially from Apple and Google.


  1. hi i want to jail break and unlock a iphone 3G 4.2.1, 05.15.04. Can this be done without loosing GPS. I dont understand what relying on unlock means?

  2. I am new to this, I am trying to unlock an iphone 3g 4.2.1 software, 5.15.04 firmware. Someone told me I have to first jailbreak the phone in order to unlock it. I wanna unlock it is because the phone was used with another carrier, and I am not using same carrier. please help…

    1. Hi, you will have to use the latest version of Sn0wbreeze that is 2.5.1 and build a custom iOS 4.3.1 while selecting the update to iPad baseband option. But it will result in loss of GPS but you will be able to use any SIM after installing Ultrasnow from Cydia.

  3. i try to jailbreak already, but stuck at the last step (i hold the home button more than 1 minit, but cannot receive the DONE message).

  4. I can not my ipod and I always have to reboot.
    what should I do???
    ich kann meinen ipod nich mehr an machen und muss ihn immer rebooten.
    was soll ich machen???

  5. my iphone 4 got stuck after the jailbreak..its been stuck on the apple sign for the past 2 hrs..not even being detected when i connet on the laptop. What should i do? Call apple care.! I already treid turning it off and than on again

  6. I have a 3Gs w/iOS 4.1 and 05.15.04 firmware. I already jailbroke it w/ LimeRain. Here is my question. I want to be able to have full data capabilities which I currently don’t because my phones not activated through apple/iTunes or whatever. Currently i only have web or data when using wi-fi. How do I add a “samspref repo” into cydia or find the right source? Heard I could patch in Redsn0w add on then add the samspref repo. Hoping not to have to re-jailbreak. Can u help me? Thank you.

  7. i keep getting to the final step after the 3 steps and it says there’s an unexpected error and to try again and switch usb ports

  8. I jailbroke my phone already, but I wanted to add the multi-tasking feature on my iphone 3G. I didn’t originally click on that when I was installing redsnow…how do I go back and add this feature?

  9. ok so last night i tried your tutorial and i got the final steps where it says ” Exploiting with limera1n” and the bar finishes up and it stop at the very end. i let it sit there for about 7 hours and still nothing …. any insight ?

  10. I jail broke my phone this way for my iphone 3g with the 4.2.1 update and I cant get my carrier to work. my carrier is ukraine-MTS

  11. if i select 4.1 and it jailbreaks it with that ips, will it still be 4.1 in the end or 4.2.1 ? cuz at the beging of the steps u said select 4.1 and the last step u said it will be 4.2.1

  12. can you help me about my iphone4 version 4.2.1 is already jailbreak. but if the battery is empty or switch off mode , my phone cannot open the only thing i do is to plug in to my computer to reboot my iphone

  13. I had tried to no avail to jailbreak or downgrade my iphone 3G (running 4.1) at least 9 times with every program out there. (redsnow, greenpoison, pwnage, snowbreeze, limera1n.
    my ispw that i was using for a restore each time finaly stopped working in itunes.
    it left me no choice but to update to 4.21! I uninstalled itunes and re installed with itunes 10.
    Then I came across REDSNOW for 4.21!!! It worked right out of the gate. I am running cydia and no speed or battery issues. I can reboot device and respring and cydia is still working (not sure if its tethered or not, but it doesnt appear to be. (3G phone anyway)

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