Downgrade iOS 4.2 to Previous Jailbreakable iOS version

A new jailbreak for iOS 4.1 and hopefully for iOS 4.2 too  is coming soon, but if you have updated your iPhone/iPod/iPad to iOS 4.2 which is not jailbreakable yet, here is simple guide to downgrade iOS 4.2 to previous version. Moreover, iOS 4.2 also contains new baseband which makes it impossible to unlock using existing UltraSnow version.

It is to inform you that this iOS 4.2 downgrading will work only if you have saved the SHSH blobs of respective firmware you are downgrading to.

Step 1: Download the required iOS version for your iDevice. (links at the bottom of this post).

Step 2: Tweak the host file present on your PC to trick the iTunes that you are connected to Apple servers. If you have got iPhone 3G and/or iPod Touch 2G (Non-MC model), skip this step.


  • Open Notepad with administrator privileges and then right-click on the icon of notepad and click on “Open as administrator”
  • Now that Notepad is open. Go to folder C:/WINDOWS/system32/drivers/etc and open the file
  • Add the following line at the end of the document and save it: (as shown in picture below)


  • Navigate to Go -> Go to Folder and enter the path /etc
  • Open the file hosts with TextEdit, add the following string save the file to your desktop.
  • Now return to the previous folder by following the same method and copy the text within this file by replacing the original file (If prompted for a password enter it and click OK)

downgrade ios 4.2

Step 3: Put your iDevice into DFU Mode. For this purpose follow the steps below:

  1. Open iTunes and connect your phone with your PC.
  2. Press and hold the Home and Sleep/Wake buttons at the same time.
  3. Keep holding the both buttons for at least 10 sec and then release the Sleep/Wake button but keep pressed the Home button.
  4. Soon iTunes will show a pop up that a phone has been found in recovery mode.

If the screen of iPhone is blank (black), you are in DFU Mode otherwise disconnect it, restart and retry to enable the DFU mode.

Step 4: Now in the iTunes hold down the Shift (for Win users) / Alt (for Mac users) and click the restore button.

Step 5: Select the required downloaded firmware and let the restore process begin.

iTunes will bring up error 10151013 or 1011 message. Don’t worry, it’s normal. You’ve successfully downgraded your iPhone/iPod Touch firmware.

Step 6: After the successful downgrade to previous iOS version, now you need to get out of recovery mode. For this purpose, download and run the TinyUmbrella and click the “Kick Device Out of Recovery” button on tinyumbralla.

Step 7: Now use the JailbreakMe to jailbreak your phone and Ultrasnow 1.1 to unlock it.


Disclaimer: This guide is for educational purpose only. Don’t follow it if you don’t know what you are going to do. We are not responsible for any type of loss of damage to anything.

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Updated 11 years agoCategorized as Jailbreak

By A. Usman

Loves new tech, especially from Apple and Google.

View all of A. Usman's posts.

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