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Downgrade iPhone & iPod Touch from iOS 4.2.1 to 4.1, 4.0.2, 4.0.1

by sork / December 29, 2010 12:03 AM EST

Hello iPhone users, with the official release of the new iOS 4.2, Many iDevice users have updated their devices, for which there is still no stable jailbreak. Furthermore, this IOS It raises our baseband, making it impossible to unlock with the current version of Ultrasn0w. So if you have a jailbroken and unlocked iDevice, it's best to stay away from this new firmware until an official jailbreak tool is available for download, and of course, here at [website/platform name]. iPhoneate.com We will keep you informed about this.

However, if you have updated to iOS 4.2 and now want to downgrade back to iOS 4.1 / 4.0.2 or 4.0.1, follow this guide. It will only work if you have saved SHSH blobs Blobs for the respective firmware you want to downgrade, I've already posted what they are on iphoneate, but to have saved them, you had to know what they were beforehand. I'm posting the thread for those who don't know and haven't saved them yet.

Requirements:


Let's start:

Step 1: Download the necessary files, i.e., the old ipsw firmware that you want to downgrade to.

Step 2: Put the device into DFU mode (not recovery mode), as follows:

  1. Connect iPhone to your computer.
  2. Turn off your iPhone.
  3. Launch iTunes.
  4. Press and hold the power and Home buttons together for 10 seconds or less.
  5. Release the power button but continue holding the Home button until your computer recognizes the new USB device.
  6. iTunes will now recognize your iPhone.

Note: Your iPhone screen should currently be blank (black). If it's not, then it's most likely in recovery mode, not DFU mode.

(Step 3 is for iPhone 4, iPad, iPhone 3GS, iPod touch 4G, 3G, 2G (MC Models) users. If you have an iPhone 3G or iPod touch 2G (non-MC Models), skip step 3 and continue from step 4.)

Step 3: This step applies to iPhone 4, iPhone 3GS, iPod touch 3G, and iPod touch 2G (MC models) devices that have their SHSH blobs (ECID SHSH) saved in Cydia for downgrading. If you don't have your SHSH blob files saved, you cannot downgrade the devices mentioned.

So, what you'll do is trick iTunes into thinking it's linked on Apple's servers, while in reality, you'll be changing the address to Saurik's server.

  • Go to C:Windows/System32/drivers/etc and look for the file “hosts".

In Mac OS X you can reach the “/etc/” directory by going through “Go to Folder"from Finder."

Open the file "hosts" in Notepad (Windows) or TextEdit (Mac OS X) and add the line: 74.208.105.171 gs.apple.com

Now simply save this file and you'll be ready to begin!

Note: For Windows 7 and Vista: Start “Notepad"with administrator privileges by right-clicking on "Notepad” and click on the option “Run as Administrator".

Note: For Mac OS X: Make sure you have full read and write access to your account when saving the hosts file. If you still get a permission error, simply copy the hosts file to your desktop, make the necessary changes, and then replace the original file in the directory./ etc /".

Step 4: Now you'll need to restore your iPhone or iPod touch to the firmware you downloaded from the step 1. Click the phone icon in the iTunes sidebar. Now press and hold the left key “old“ (option) located on Mac (Left “Shift“button in Windows) on the keyboard and then click on “Restore" (No "Update”), located in iTunes and then release the button.

This will prompt iTunes to ask you to select the location for the downloaded firmware file. Select the ipsw file and click “Open".

Step 5: Now wait and enjoy as iTunes does the rest of the work. This involves a series of automated steps. Be patient during this stage and don't do anything unexpected. Wait while iTunes installs the firmware on your iPhone or iPod touch. Your iPhone screen will display a progress bar indicating the installation progress. At some point, iTunes will display errors 1011, 1013, or 1015. This is normal; simply ignore these errors, as the firmware will be successfully installed on your device.

Step 6: The iPhone will at this point be in recovery mode, displaying a message “Connect to iTunes"" on the screen. To take your device out of recovery mode, download this program called TinyUmbrella. (Windows / Mac)Run it and click the button.Kick Device Out of Recovery"The device will restart normally."

Step 7: Last but not least, you must now remove the line 74.208.105.171 gs.apple.com from the hosts file so that you can receive future Apple updates through iTunes.