In the event you upgraded to iOS 4.2.1 and now want to downgrade back to iOS 4.1 / 4.0.2 / 4.0.1, follow the instructions posted below to downgrade iOS 4.2 on iPhone 4, 3GS, 3G, iPod touch and iPad to iOS 4.1 / 4.0.x.

NOTE: This guide will only work if you have  SHSH blobs saved for the respective firmware you downgrading to.

IOS 4.2.1 iPhone Downgrade

  1. Download the required old ipsw firmware files to which you want to downgrade iOS 4.1/iOS 4.0.1/ iOS 4.2.1.
  2. Set up your device in DFU mode.
  • Put your device into DFU mode (not recovery mode).
  • Connect your iPhone to your computer.
  • Turn iPhone off.
  • Start iTunes.
  • Hold Power and Home buttons together for 10 seconds or so.
  • Release Power button but keep holding the Home button until your computer recognizes a new USB device.
  • iTunes will now recognize your iPhone.
  • Note: Your iPhone screen at this time should be blank (black in color), if not, then you are most likely in Recovery Mode, not DFU mode.

Doing so, connect your device to computer and turn it off. Now Start iTunes and hold the Power + Hold button together for around 10 seconds. And now release the Power button but continue Home button pressed until your computer recognizes a new USB device. You will see iTunes logo and then “Connect to iTunes” will be displayed. Now you can release the Home button.

3.  Steps 4 and 5 should be followed by iPhone 3G or iPod touch 2G (non-MC model) users. If you have iPhone 4, iPad. iPhone 3GS, iPod touch 4G, 3G, 2G (MC Model) go directly to step 6.   
4.  Go to the path “c:windowssystem32driversetc” in windows and open file “hosts” file in notepad. Mac users should go to path “/etc/” by going through “Go -> Go to Folder” from Finder and open the “hosts” file with text editor.

5. Add the string “” at the end of the file. This step enables to redirect requests for certificates for authenticity that iTunes will make to the Saurik server. Save the modified file.  

Windows users

  • 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:

Mac users

  • Navigate to Go -> Go to Folder and enter the path /etc
  • Open the file hosts with TextEdit, add the following string and 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)


6. You have to restore to the old firmware that is downloaded in Step 1. For doing so, click on phone icon in the sidebar in iTunes. Press and hold left “Alt” button on Mac (Left “Shift” button on Windows) on the keyboard and then click on “Restore” button in the iTunes and then release this button.

7. A prompt will appear to select the old firmware file. Select the ipsw file to restore and click “Open”.

8. Wait for sometime while iTunes is restoring firmware on your device with some automated steps. You will see a progress bar is displayed at the iPhone screen. Wait until it completes. If, you see any error like 1004 or 1015 don’t panic as that is normal error which iTunes throw.

9. Your iPhone will go into recovery mode and “connect to iTunes” message will appear on the screen.  Download TinyUmbrella on your computer and run it. Now click on “Kick Device Out of Recovery” button. Your iPhone will be restarted now.



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