How To Jailbreak your iPhone 3G running 4.2.1 Firmware with Windows 7 and Redsn0w.

A step by step guide on how to Jailbreak your iPhone 3G using Windows 7 and Redsn0w. If you you dont have any luck doing the jailbreak you can always restore your iPhone from iTunes.
Download Redsn0w from our downloads page.

So I made this video to help others Jailbreak their iPhones. Because about one year ago I tried to jailbreak my iPhone unsuccessfully.
What is this jailbreak I speak of? Well if you think of the term jailbreak you imagine a prisoner escaping from jail. Well that is essentially what you are doing with your iPhone you are breaking it out of jail and relaxing all the restrictions that Apple has placed on the iPhone. If you want to learn more about what is the difference between jailbreak and unlock you can read my article on it here. Jail breaking allows you to install Apps and configure your iPhone that would otherwise be locked down by Apple’s default settings. A good example of a great Apo that will install on a jail broken iPhone is Veency and you can see my video here.

Before attempting any funny business with your iPhone or iOS device, you should always do a backup in iTunes and you can find the video on how to here. Once you have backed up your iPhone and you are happy that all your data is safe you are ready to Jailbreak it.

Step 1. Go into your setting menu, general and turn off Auto-lock and Passcode Lock. Make sure both these settings are off as they may interfere with the jailbreak.
Step 2. Scroll up and go into About, and make a note of the firmware version.
Step 3. Download redsn0w from our downloads section here. There is a Windows and Mac version that you can download.
Step 4. Install redsn0w and run the application. Plug in your iPhone to the USB port and make sure the driver for the iPhone installs correctly. If it doesn’t try restarting your PC or Mac with your iPhone plugged into the USB port. This will normally resolve driver issues, because the driver detects the iPhone and installs the driver on start up.
Step 5. Make sure you iPhone is turned off and still plugged in.
Step 6. Ok you need to now put your iPhone in DFU mode. To do this you need to Hold down the power button for 3 seconds. Without releasing the Power button, also hold down the Home (bottom center)button for 10 seconds. Without releasing the Home button, release the Power button, BUT KEEP holding the Home button for 15 seconds.
Step 7. In the redsn0w program it should say waiting for reboot. And on your iPhone will say downloading jailbreak data. Once redsn0w says done you can actually disconnect the USB cable from your iPhone and it will continue to install.
Step 8. The iPhone should reboot and once it does this you can login and scroll across to your Apps and you should see a brown Cydia App. If you have this then you have been successful in jail breaking your iPhone.

One last thing I should mention, the jailbreak process does not always go smoothly. The most annoying error is USB communication error. You can see my video on how to fix this error here.

Good luck guys and have fun.


52 thoughts on “How To Jailbreak your iPhone 3G running 4.2.1 Firmware with Windows 7 and Redsn0w.

  1. Thanks so much for the video on how to jailbrake iphone 3g,its really help.But i will like to ask you for a help again,my iphone wi-fi says N/A.can you please tell me how to go about this please by sending me a mail on how to go about it.Thanks again for the help.

  2. my home button not working too well so i found this program that can put my phone in DFU mode but when i try it with redsnow it doesn’t work redsnow tell me to Google or YouTube how to put my iPhone in dfu mode u have any suggestion

    • Hi Posh
      Have you tried an App that allows you to have Home button on the touch screen ?
      Go to Settings, General and then scroll down to Accessibility. Tap AssistiveTouch, and then slide AssistiveTouch into the ON position.
      This may only work for newer phones, but maybe have a search for an App on iTunes.

  3. Hi, I tried to jailbreak my iphone 3GS and it worked, then tried to install facebook app following your instructions from another post which was about it. I installed FB app and when I use it it works for about 10 seconds and then crushes and I’m back in home menu.. Can you help me with this problem, please? ๐Ÿ™

  4. Hi i followed the redsn0w program and it came to a bit where i had to hold the power button, then home button, and i did it, and then the usb communication error popped up, and now my iphone will not turn on. HELP?!!!

    • Hi Joe
      Try putting the phone in DFU mode again. Its not broken, just in DFU mode.
      If that doesn’t work you can follow my USB communication error video here.
      Good luck. Let me know how you get on.

  5. My phone just goes to a black (backlit screen). Goes through the process fine, the app on the PC screen loads the software and says done but nothing actually happens on the phone itself. Just sits there with a black blank screen.

    Any ideas

    • Hi Alfonse
      Yes, I have seen that before. I would suggest doing a backup and restore of the original firmware which you can find here.
      Backup video here.
      Restore video here.
      Then try running the process again.
      Good luck.

  6. i did it all it said downloading jailbreak data then a black screen appeared with a white writing and it stopped there. what should i do?

  7. Hi! is this supposed to work with windows vista as well? because the first step didn’t work for me.. if not do you know how to do it with vista? thanks!

  8. Err. do you have a tutorial on how to reformat iphone 3g? :\ i think my phone is running very slow, can even load my music on itools. :< Thank you in advence bro.

  9. Hi
    I am trying to jailbreak my iPhone 3G, iOS 4.2.1 (8C148) with redsn0w, folloving your instructions, but i always stuck at the moment when on the PC screen there is writen “The rest of this process takes place on your device” and :Done!: and the screen of iphone is just black and nothing is happenning. I already tryied redsn0w 0.9.15b3, b2, b1 but with the same resoult. I was trying it more times but it is always the same. Any ideas what should I do? Thanks a lot.

    • Hi Tomas
      Its a difficult one and doesn’t always run smoothly.
      It could even be that the jailbreak isn’t supported anymore for such old phones. I say this because recently they removed App Sync support for 4.2.1 firmware. This means even if you were able to jailbreak you might not be able to get the Apps to sync properly.
      Make sure you phone is fully charged.
      Try a fresh firmware install of 4.2.1 before the jailbreak ?

      • Thanks for answer, finaly i solve the problem by doing the same but on another computer. On both computers i had USB connection problem, which I solved by manualy selecting IPSW in redsn0w. So now I have jailbroken phone and cydia, but as you said it looks that there is no more appsync and appcake for iOS 4.2.1 ๐Ÿ™ The reason I was making jailbreak was that I wanted to install aplications such as viber and skype on my iPhone 3G so I hope I will find some way.

  10. Hi

    Redsn0w says it’s looking for a build, and is unable to start the jailbreak due to the build missing. I tried to get that error message back on the screen by following the steps again, but redsn0w just kept saying that no device was detected.

    Could you please help me with this? The firmware version is 6.1.6 (10B500) Iphone 3.


    • Hi Ajsela M
      Yes, no device detect means that the iPhone driver has not been installed.
      Keep your iPhone plugged into the USB and restart the computer.
      On start up the computer should install the driver. Run it again and it should detect the device.
      Let me know if it doesn’t.

      • Hi Matt

        Thanks for your quick reply.

        I tried it again, this time with the phone turned on because in the instructions redsn0w says that if you have an earlier version than A4, but older than 5.1.1 (mine’s 6.1.6) you can leave the phone in normal mode.

        So redsn0w started the reboot, but then the following message came up:
        Missing Keys.plist data for this build:
        Device: Iphone 3GS
        ECID: 3869062856110
        Build: Iphone 2, 1_6.1.6_10B500

        Is there a way to fix this problem?



        • Hi Ajsela M,
          Umm, the way I had most success was to make sure there was a fresh version of 4.2.1 firmware on the device and then try the jailbreak after that.
          Are you trying to jailbreak the device or downgrade it ?

          • Hi Matt

            I’m trying to jailbreak this iphone because I want to install Viber.

            I searched the web on how to install Viber on ios 6.1.6, and your videos came up. Is there another way you know how to install Viber on this device without jailbreaking it?



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