Apple has recently released iOS 4.2 Beta for iPhone 4, iPhone 3GS, iPhone 3G and iPod Touch 2G and 3G and iPad only for developers. You might want to downgrade from iOS 4.2 to iOS 4.1 / iOS 4.0.1 /iOS 4.0.2 firmware due to any problems occurring or you cannot still jailbreak iOS 4.2. Below is a simple step by step guide for both windows and Mac users to downgrade to iOS 4.1 or iOS 4.0.1 or iOS 4.0.2 from iOS 4.2.
NOTE: Only users who have saved their ECIDs with SHSH to Cydia Server for iOS 4.1, iOS 4.0.1 or iOS 4.0.2 must follow this guide. If you don’t have ECIDs please don’t go through this procedure as it can end up in screwing up your device OS. The ECIDs must be saved before up gradating to iOS 4.1 else you cannot downgrade after updating iOS 4.2.
Guide to Downgrade iOS 4.2 to iOS 4.1/iOS 4.0.1/ iOS 4.0.2 Firmware
- Download the required old ipsw firmware files to which you want to downgrade iOS 4.1/iOS 4.0.1/ iOS 4.2.1.
- Set up your device in DFU mode. For 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.
- 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.
- 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.
- Add the string “126.96.36.199 gs.apple.com” 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.
- 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.
- A prompt will appear to select the old firmware file. Select the ipsw file to restore and click “Open”.
- 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.
- 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.
Now, you have successfully downgraded from iOS 4.2 to iOS 4.1/4.0.1/4.0.2. If you are on iOS 4.0.1