Chronic Dev Team Releases Greenpois0n RC5 4.2.1 untethered jailbreak tutorial

The Chronic Dev Team has finally released RC5 which is an untethered jailbreak for 4.2.1. Right now this is only for and , a Linux version should be out shortly. This tutorial is how install Greenpois0n RC5 on iPhone, iPad and iPod Touch 4.2.1 and will work for Windows or Mac.

UPDATE: A new version of Greenpois0n RC5 has been released today, February 4th, in order to fix some issues. The download links below have been updated.

Greenpois0n RC6.1 for OSX
Greenpois0n RC6.1 for Windows


- iPod Touch 2G (all bootroms)
- iPod Touch 3G
- iPod Touch 4G
- iPad 1G
- iPhone 3Gs (all bootroms)
- iPhone 4
- iPhone 4 Verizon
-AppleTV 2G is supported, please see our Greenpois0n RC6 post


- a supported device (see above)
- the device should run iOS 4.2.1. Please check on the device in the Settings -> General -> About page.
If your device is running an older version, please upgrade iOS first using iTunes.
*** If you want to SIM Unlock, preserve your baseband using TinyUmbrella(iPhone 4 ONLY) ***
- at least MacOSX 10.5
- OSX in a VM won't work
- a working internet connection


- if your device is jailbroken with iPhone Dev Team's Monte, please restore to fresh 4.2.1. first
- if Cydia doesn't show up after Loader, you may need to reboot the device
- this version of greenpois0n doesn't include a patched activation system. You'll need to activate your device using iTunes



The following instructions will help you jailbreak iOS 4.2.1 on iPhone 4, 3GS, iPod Touch 2G/3G/4G, Apple TV and Apple TV 2G using GreensPois0n.

NOTE: If your iPhone 4 relies on an unlock, do not update to iOS 4.2.1 yet as doing so will upgrade your baseband, making it impossible for now to unlock.

Step 1: Download GreenPois0n from from the links above.

Step 2: Connect your iPhone via USB to your computer and click on “Jailbreak” as seen in the screenshot below.

Step 3: Now follow the following onscreen instructions to enter DFU mode or click here to see a video tutorial on how to enter DFU mode.

  • Press and hold the sleep button for 2 seconds
  • Continue holding sleep; press and hold home for 10 seconds.
  • Release sleep button; continue holding home for 10 seconds or until Greenpois0n detects your device.

Step 4: Your device is now ready for jailbreak. Greenpois0n will say "complete" and you will see lines of text scrolling on your device.

Step 5: Your iPhone, iPad or iPod touch should now be successfully jailbroken on iOS 4.2.1. Now start “Loader” found on the homescreen and install Cydia.

This is it! You are done !

Download iOS 4.2.1 for iPhone 4, 3GS, iPod touch 4G / 3G / 2G and iPad

When you jailbreak with GP RC5 you will see 4 errors:

Unable to find
Unable to find fs_mount
Unable to find fs_unmount
Unable to find

followed by "Greenpoison Initialized" these errors are normal, however, some users(including me) have been getting stuck at that screen. The screen changes pretty quick after that so if you are stuck at Greenpoison Initialized for more than like 15 seconds you probably have to try again. A fix for this issue is basically just trial and error. Personally I had to restart my iPhone 15 times before Greenpois0n actually went all the way through. One of our members, iBrandon, suggested to continue holding the home button down even after you're in DFU mode. This worked for me once, but the second time I just restarted and it worked. downloading Cydia problems:

Use Redsn0w to install Cydia, select ONLY the option "install Cydia"

Please note that your download may take a while as the servers are under a heavy load as the jailbreak has just been released.

Also, the "Big Surprise" that we mentioned the other day is that the new version of GreePois0n will allow you to set custom animated boot logos for your devices.

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  • idestruct

    I have a pc.

    But what do you think are the odds of this working in vmware ??

    • JaeM1llz

      I’ve talked to 3 different people who’ve tried it with VMWare on 10.6.6 and all 3 of them reported nothing happening after putting their device into DFU mode, but give it a shot. Otherwise, the Windows version will be out soon hopefully, they’re just finishing packaging it up.

      • idestruct

        I did.. I’m on 10.6.4. No luck either.. I have the same problem it goes in to DFU mode but it just doesn’t send the jailbreak files.. Oh well hopefully windows will be here soon

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  • dristy

    is that the jailbreaking and the unlock both are the same thing.?..i just wanna unlock my device which is 3gs 4.2.1 version so that i can use any sim on it…so what i have to do…jailbreak first then unlock or just unlock..pls need details

    • JaeM1llz

      No, jailbreaking and unlocking are not the same thing, and you must jailbreak in order to unlock, however if you are already on 4.2.1 it is impossible to unlock at this point because there is no unlock for the newest baseband

  • Ali

    nice TUTORIAL:

    thanks coooooooooooool i did it thanks to this website and to the person who did this i have cydia on my iphone

    • JaeM1llz

      No problem, I am glad that we were able to help!

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  • David

    I have an Imac G5 with OSX 10.5.8 but greenpoison still doesnt work on it. why?

  • Tonino

    Hi JaeM1llz, Can you advise the button combo (step 3) when using Greenpois0n RC5 to jailbreak the Apple TV2? Is there anything other than the steps you’ve used here that is different when applying it to Apple TV2? cheers.

    • JaeM1llz

      Currently AppleTV 2G is not supported. Support for ATV2 should be added in RC6

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  • Tonino

    Thanks for the quick response. By ‘unsupported’ do you mean that this jailbreak will not work f applied to the Apple TV2? Sorry if that sounds obvious but, the Apple TV2 is listed in the ‘Supported Devices’ list with a caveat, so it’s a little confusing. I wondered whether it means: Can jailbreak it but no ongoing support? Cheers.

    • JaeM1llz

      Correct, RC5 will not work on ATV2. It is listed under supported devices but it also says that support will be added in RC6 or in other words, you will be able to use Greenpois0n RC6 to jailbreak ATV2. Hope that clears things up! I have edited the post to try and make it more clear.

  • David_

    Windows version working fine here on iphone 3gs (old boot) 4.2.1

    thanks dev team!

    • thescragster

      Thanks David, nice to hear your success :) Congrats

  • danka

    What’s the difference between the GP R5_b3 file size (4,874,558 bytes) and the ‘other’ GP R5 (4,870,498 bytes)?

    I installed the latter on an iPhone 3GS with just a broken iBook issue but everything else is great so far.

    Does the GP R5_b3 resolve issues worthy of knowing?

  • Ganni

    I have iphone 3gs new bootrom with os: 4.2.1 with BB 5.15.04, this jailbreak will work on device?

    • thescragster

      Hi Ganni,

      Yes this jailbreak works for all devices, your device is included :)

      Let us know how you get on.

      • Dan

        This worked for me the first time. Well done Chronic Dev team and thanks to thescragster for the support. (all the answers and questions I needed were answered and asked by all you people) so thank you.

      • Dan

        Is anyone else experiencing cydia time-outs

        • thescragster

          Hi Dan,

          We have not had reports from other users having this problem how-ever I am not surprised that you are having this error. This often happens when a new jailbreak has just been released. It happens because so many people have just install Cydia onto their devices so the server is being overloaded.

          Try leaving it and coming back in a few hours.

          Let us know how you get on

  • Barlosk1

    I updated to 4.2, through iTunes, from 4.0.1 on my iPhone 4. Downloaded rc5 b2 from the greenpois0n website. Jailbroke my phone with no problems at all … Was experiencing a really slow cydia and time-outs but thats just cuz everyone is using it at the same time. As of now it seemed to speed up a bit. just a useful hint, do exactly what it says on the jailbreak program when jailbreaking … I went into dfu mode by myself without listening to what it told me to do and it didnt work, I then did what it said and it worked perfectly.

    • JaeM1llz

      It works either way. I put my device into DFU mode before even opening Greenpois0n and then as soon as I hit jailbreak it just skipped right to the jailbreaking process instead of displaying the DFU mode instructions. Those instructions are only there to help people who are new to jailbreaking, but as long as you get your device into DFU mode it doesnt matter when you do it.

      Glad everything worked out for you! I also want to reiterate that if you guys are having issues getting Cydia to install because the server is lagging you can just use Redsn0w to install Cydia.

  • StruggleStreet

    I have an iPhone 4 on 4.2.1 and greenpoison just wont seem to work for me.It wont load the jailbreak files, it just stays in DFU mode then reboots (jailbreak failed comes up on greenpoison)

    using windows btw

    Am i timing the steps wrong possibly? Ive tried it like 15 times. I have baseband 03.10.01, but that shouldnt effect the jailbreak rite?

    Am i missing anything here? lol

    heeeeeelp lol

    • JaeM1llz

      Just get into DFU mode first and then open Greenpois0n sometimes its hard to keep up with the instructions on the screen

      • StruggleStreet

        Thanks for the reply,

        I have tried this method now, iTunes recognises the iPhone as being in DFU mode. But when i go through greenposi0n it just reboots. May be its my work PC or something… but im lost. I dont have an active USIM in, would that effect anything? Or version of iTunes perhaps?

        Ill try again when i finish work, but if you had any further tips/Ideas that would be much appreciated.


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  • Ceetee

    Hi there,

    My iphone for running 4.2.1 and jailbroken using Redsnow 0.9.6b4, do i require to restore before applying this jailbreak?

    • JaeM1llz

      No, you can just use greenpois0n right over the top of it to make it untethered just like it says in the post. However, if it doesnt work you will have to restore first.

  • bn

    I have an 3g on 4.2.1 and have downloaded greenpoison for window and have fallowed instuctions to a t as far as i can tell… and after i go through holding down sleep key, home key, etc…. it keeps telling me to “try again” i am a novice at this sort of thing i must be missing somthing, any help of advice.

    • JaeM1llz

      Follow this video tutorial to get your device into DFU mode, then start Greenpois0n and click jailbreak, it should just skip right to the jailbreaking process

  • Andrey

    I have an iPhone 3GS running on old boot (5.8) I want to update it to 4.2. Can I have a untethers jailbreak and unlock my phone for tmobile as well? On 4.2?

    • JaeM1llz

      You must download a custom/prejailbroken 4.2.1 firmware(or create one yourself) and restore it in Pwned-DFU mode in order to update to 4.2.1 and maintain your baseband.

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  • Travis

    Whenever I download greenpois0n I open it and iTunes opens up any ideas I really wanna jailbreak

    • JaeM1llz

      Put your device into DFU mode first and the open greenpois0n

  • Matthew

    Do i need itunes to jailbreak

  • Matthew

    I have heard on arcticals online that it can block up your ipod and erase data and if you touch your ipod while jailbreaking it can crash your computer and if i have my ipod break while jailbrocken then your screwed please reply asap

  • Matthew

    And i also heard that if i update while jailbrocken then i’m stuck forever

    • JaeM1llz

      No, you do not need iTunes to jailbreak. Whatever you have heard about jailbreaking it is all wrong so just forget you ever heard it. It will not do anything to your iPod. Obviously you don’t want to unplug your iPod while it is jailbreaking or the jailbreak will fail and you will have to restore which will erase all your content. And no, if you update you are not stuck there forever, as long as you back up your SHSH files you can always downgrade firmware. Otherwise you just have to wait until the next jailbreak is released.

  • Matthew

    When you jailbreak does it wipe your ipod memory and take off all the apps???????? Reply asap

    • JaeM1llz

      No, jailbreaking itself will not remove anything from your iDevice. The only time you will lose any information is when you do a “restore” in iTunes. Thanks!

  • Matthew

    When u “restore” do still have my app info when i use my latest backup

  • Matthew

    I cannot backup my info or use greenpois0n and i want 2 use on my ipod what would u suggest i do cuz i really want 2 jailbreak now so please reply ASAP

    • JaeM1llz

      It’s not possible to use the PDF exploit that allowed that website to work was patched back in firmware 4.0.2, your best option to jailbreak is greenpois0n.

  • Matthew

    Thx, next time i have acess to a computer i will and thank u so much for answering all my questions

  • James

    Can I jailbreak my iPhone 4 if it is still running 4.1 firmware???

  • James

    I tried using greenpois0n but it wouldn’t work? Could that be due to the computer not meeting the requirements, or will it not work period on my phone?

    • JaeM1llz

      Yes greenpois0n works fine on iphone4 4.1. I doubt tour computer is incompatible because the requirements aren’t high it’ll work on any crappy old computer but try it on a different one anyway

  • James

    Well one of my good friends said that because my iPhone 4 is the MC6 model blah blah, rather than an MB6 model blah blah whatever, that I’m not able to jailbreak it yet. So am I screwed for now?

    • JaeM1llz

      All models of iPhone4 are jailbreakable so your friend doesn’t know what he’s talking about :P

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  • Va7db

    OK Guy’s-n-Gal’s, I’m an old fella with a problem, hopefully someone can offer a suggestion.
    I have an iPhone 3G running ios 4.2.1, I should add that I managed a successful jailbreak on my iPad2 but cannot get the iPhone to do the same.
    I have read and re-read and watched countless video’s and I think I’m doing everything right.
    I’m running WinXP so downloaded the Win version of gp_win_rc6.1, backed up the iPhone, closed iTunes and followed the instructions on pressing button sequence……I’ve tried three times now with a complete restore / reload in between and always get the same result.
    I can never get greenpois0n to see the device, it always tells me to “try again” and then of course I have to restore before I can get iTunes to see the phone again.
    Any suggestions welcome….. Thanks in advance.     Dave

    • JaeM1llz

      You cannot use Greenpois0n to jailbreak iPhone 3G, it is not supported. You must use redsn0w, sn0wbreeze.

      • Va7db

        Thanks for the info, please excuse my ignorance, I did look up redsn0w but it was asking me to also have ios 4.3.3 which I didn’t think would work on my old 3G iPhone……can you please tell me if snowbreeze is an alternative jailbreak tool or a file I need during the use of redsn0w and also which is the correct version of redsn0w as I looked and am a bit confused……..again sorry for my ignorance, at 65 and a hardware guy all this firmware is a bit new to me. :-)
        Huge thanks for any thoughts……Dave

        • JaeM1llz

          Redsn0w works fine for 4.2.1, I’m pretty sure any of the latest versions will work, but the version specifically released for 4.2.1 was 0.9.6rc16, but you will need to download a 4.2.1 IPSW file if you want to use that version because older versions of Redsn0w do not auto-detect firmware or download the necessary pieces like the newer versions do.

          • Va7db

            Thanks so much for taking the time to reply ! I will look for both and let you know how I get on…

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