RedSn0w was recently updated to jailbreak iOS 4.2.1. While this is excellent news, it doesn’t come without its drawbacks as only the iPhone 3G, older iPhone 3GS, and non-MC iPod touch 2G get the untethered jailbreak.

Other devices get a tethered jailbreak, which means that every time you reboot your iPhone, you will have to plug your iPhone in your computer, and launch RedSn0w to start your iPhone. Hopefully the Dev Team will come up with a way to bypass this soon.

If you are an unlocker, you should not update to 4.2.1 yet. You will lose your chances of unlocking. Wait for PwnageTool, which should be updated relatively soon.

This step by step guide will show you how to jailbreak your iPhone iOS 4.2.1 with RedSn0w. This tutorial was made using an iPhone 3GS but the steps are the same, no matter what device you are using…

Step 1: Make sure iTunes is updated to its latest version. Make sure your iPhone is on 4.2.1. If not, update it via iTunes.

Step 2: Download RedSn0w 0.9.6b4 and the firmware for your device from our downloads section.

Step 3: Launch RedSn0w and browse for the firmware you downloaded in step 2.

Step 4: Select to Install Cydia.

Step 5: Make sure your iPhone is turned off and plugged in your computer. If it’s not, plug it in, then turn it off. Click next, and be ready to get your iPhone in DFU mode.

Step 6: Hold the Home and Power button together for 10 seconds. Release the Power button while still holding the Home button for a few seconds.

Step 7: Your iPhone will run lines of codes. When it’s done. Click Finish. You’re done!

Now if you have a newer device such as the iPhone 4, every time you reboot your iPhone, you will have to launch RedSn0w and choose the “Just boot tethered right now” option to boot your iPhone.

There is currently no unlock for iOS 4.2.1 but we will keep you updated as soon as it is released.

Any question, feel free to ask below.

  • james

    sorry i know this is a daft question but i done the latest version and was wondering if its still possible to use the normal app store aswell as installous

  • ADDE

    Im trying to jailbreak my 3G. But it´s stuck when redsn0w want to upload ramdisk.
    I´m useing iOS 4.2.1 and Redsn0w 0.9.6RC8.

    • Sikkmade

      I’m having the same problem…is the a way to solve it…

      • Fuck u u need a life u fuckin geek

    • Sikkmade

      I’m having the same problem…is there a way to solve it…

      • Robert

        Why don’t you use GreenPois0n? Or if you want to preserve your baseband, PwnageTool or Sn0wbreeze? These all work.

  • Neil

    Please help. I just wanted to upgrade my iPhone 3GS 3.0 and tried this route as mentioned above. But in the middle, it showed connect to itunes logo. I went back to itunes and restored it, which said that it is uplading the latest software. After that, all the processes in redsnow went smoothly, but at the end, it is hung with apple logo and the loading dial stuck. Please help. I am in real distress.

    • Cody

      I wanna what if ur lock button dont work wht do u do bc my lock button is brook

    • Mike

      You have to hold both buttons while it shuts off and turns back on. If you let go too soon I gets stuck in load limbo.

  • Anju

    What version of Redsnow will work on my i3g updated with 4.2.1 baseband 5.15.04 and where would I find it.
    I have tried 3-4 jailbreaks and read all the comments and it seems that there is one redsnow 096b6 wud work but I have not been able to find that software to download…Please help.

  • brad

    having a hard time. just added Greenp0ison to verizon iphone 4. Loader wont open. Now I am curious if having 4.2.5, which I do, wont allow jailbreak. ???

    • Robert

      Try to JB again with GP.

    • Kevin

      1st,make sure you are connected to the internet for you can open ”loader” if it still doesn’t openning restore your retry to do it.
      Good luck

  • Amamamam

  • Kevin

    Hi everybody,does anyone know a untethered jailbreak for ipod touch 3rd generation on 4.2.1???
    Because greenpois0n isn’t working on my ipod
    Please anyone can help me?

  • hwe123

    when i download the firm ware for my ipod touch 4g, it comes as a .zip file, but redsn0w asks for a .ispw file and i can’t find it. can somebody help?

    • Pooface

      Windows? If so, slow left click on the file name, erase the zip portion and put ipsw

  • Sadgurlz

    Why is it that my cydia is blank and it can’t be opened? Can anyone help me please? I need to solve it and after installing the jailbreak ; cydia, my safari can’t work, what’s the way to solve it ? Please help ! 🙁

    • Jason Emmanuel Cruz

      Sadgurlz, trust me this will work…
      Jailbreak your iPod with redsn0w tethered jailbreak (make sure you tick the Cydia option).
      After that, go to and download the latest version of greenpois0n, run the .exe file and follow the instructions. Your iPod will be in an untethered jailbreak with Cydia up and running.

  • Robert

    Do the JB again.

  • Raindropz

    i just did the jailbreak and it worked perfectly!!! thanks!! 😉

  • Greg

    I followed the above instructions and my 3G iOS 4.2.1 phone is now frozen with the Apple logo on the screen. Has been for 15 minutes. Tried rebooting with the power button and home button depressed at the same time and it came back on with the same Apple logo. I want my phone back! Any ideas?

    • Robert

      You need to put your phone into DFU mode and do a restore.

      You can find videos on YouTube that will help you getting your phone into DFU mode.

  • andy

    when i click on the file redsnow in my doc it says file corrupt and will not open….

  • lean beef

    Is this a windows compatible JB? and if not do i need snowbreeze? Do I JB first or install snowbreeze first? I’m trying to JB my previously JB 3G with and my dumb.. upgraded to iOS 4.2. Now, having problems finding the right software to JB. Thank you.

  • JIZZ

    this fucking broke my iphone don’t do it. Now i have to pay 500 to get a new one

  • Neil Pande

    The best is to download tinyumbrella, get your SHSH and then go on with unlocking with other software. Whenever you get stuck, you can get back to your original setting if you have done that with tinyumbrella.

  • Ben

    Use it for different network when I travel

  • Jimbo

    Didn’t work on my 3G. Snagged on apple logo. Had to restore in DFU mode. Not recommended.

  • Robert

    It’s up to 4.3.1 and there are new versions of Sn0wbreez, PwnageTool, etc. They work.

  • Leanbeef

    I have a iPhone 3G iOS 4.2.1 previously jb with on os3.1. I mistakenly upgraded to 4.2. I tried downgrading it with tiny umbrella and also jb with redsnow, but When i download the firmware, neither redsnow or myself can find the appropriate firmware with an .ipsw extension. I tried changing the extension from . Zip to ipsw with no luck on Wondows.

  • Leanbeef

    I have a iPhone 3G iOS 4.2.1 previously jb with on os3.1. neither redsnow or myself can find the appropriate firmware with an .ipsw extension. I tried changing the extension from . Zip to ipsw with no luck on Wondows.

  • lean beef

    Ok, fixed the .ipsw problem. I used firefox. But now my phone has been stuck on uploasing ramdisk for about 5 mins or so. iphone 3g ios 4.2.1 previously jb w/ on os 3.1. Now using redsnow. thank you guys so much for the tips.

  • Robert

    If you rely on an unlock, be careful upgrading to 4.3.1 with a firmware only restore. I ran into a problem on a 3Gs where it wouldn’t completely restore (error code 37), and others are having the same issue. Only way to get it working was to restore the factory IPSW, which also upgraded the baseband.

  • Dmoney

    To fix the RAMDISK issue on the beta edition, you need to set the processor affinity to CPU1 for the redsn0w.exe process. This is accomplished in task manager.



  • sean

    How long does the ramdisk part take?? its been about 5 min

    • Dmoney

      If the ramdisk step is frozen, please refer to my April 7th post.



  • lloyd

    @Dmoney: I’ve done the task manager thing but it’s still not moving in the uploading ramdisk part.

  • yoz

    superb!!!changing the processor affinity to 1 done the job!muchos gracios!

  • John

    There is currently no unlock for iOS 4.2.1 but we will keep you updated as soon as it is released.

    Any question, feel free to ask below.

    That last line was a total kick in the ass. Thank God I read all the reviews / comments BEFORE I messed with my i3g 4.2.1 to jailbreak & get the tethering to work! When there’s a fix, I’ll be back to try it.

  • Jack

    My loader doesn’t want to open, and I’m connected to Internet

  • lUc

    hii guys, i have a big blem.
    i tries to jailbreak my ipod touch 2g ios 4.2.1.
    bUt the redsnOw tell me that i have a “fixed device”
    its cannot finish the process.
    what does its means ..??? what i have to do???? plzzZ help

  • Seddon Platts

    hi i have a 2g ipod touch and cannot get past the update to 4.2 in itunes I have tried all the suggestions and on 3 machines still the same (1) error. I see from the instructions above to jb I need to update the software (ios) via itunes Q can i do this without updating to 4.21 or have you any other suggestions?? Thanks SJP