Apple recently released iOS 4.3 for the iPhone 4, iPhone 3GS, iPod Touch 3G, 4G, and iPad to developers. After updating your iOS device to the latest iOS 4.3 firmware, you might face incompatibility issues with your favorite iOS apps forcing you to return to the older iOS 4.2.1, iOS 4.1, or iOS 4.0.1 firmware. If for some reason, you upgraded to iOS 4.3 and would like to downgrade to iOS 4.2.1, 4.1, or 4.0.2, follow the steps listed below (for both Mac and Windows users).

IMPORTANT:

• This process is only for those who have already saved the ECIDs with SHSH to Cydia Server for iOS 4.1, iOS 4.0.1 or iOS 4.0.2 and we are sure that you had saved it before the release of iOS 4.2.

Guide to Downgrade iOS 4.3 BETA to 4.2.1 / 4.1 iOS Firmware

Step 1:

Download the firmware file for the firmware you wish to go back to. (Download links: iOS 4.2.1, iOS 4.1, iOS 4.0.2, iOS 4.0.1)

Step 2:

Navigate to the path “c:\windows\system32\drivers\etc\” and open the hosts file in a Notepad or Wordpad. MAC users can navigate to the path “/etc/” and open the hosts file with TextEdit.

Step 3:

At the end of file add the string 74.208.105.171 gs.apple.com useful to redirect requests for certificates for authenticity that iTunes will make to the Saurik server. Follow the steps below to see how to do this:

Windows users

• Open Notepad with admin privileges, then right click on the icon of notepad and click on “Open as administrator”
• Now that the 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: 74.208.105.171 gs.apple.com

Mac users

• Navigate to Go -> Go To Folder and enter the path /etc
• Open the file hosts with TextEdit, add the following string 74.208.105.171 gs.apple.com 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)

Step 4:

You now need to set up your device in DFU (Device Firmware Update mode), to clarify, that does not mean Recovery mode. DFU mode is a mode where your iOS device will be made to force a restore of the firmware into whatever version firmware it is given. Getting your iPod Touch or iPhone into DFU mode is somewhat tricky, and it may require some patience and practice because timing is essential to get it to DFU mode and not into recovery mode.

• Open iTunes and connect your iOS device to your Mac.
• Press and hold the Home button and the Power button at the same time.
• After exactly 10 seconds release the Power button. Continue holding the home button until computer recognizes your iPhone.

After iTunes recognizes your iPod Touch or iPhone, let go of the Home button (if you don’t it will enter recovery mode and you will have to do the entire DFU process all over again.) You will know when you have put your iOS device correctly into DFU mode when the display is blank and that you do not have anything on your device.

Step 5:

Now, restore your iPhone, iPod Touch, or iPad to the firmware you downloaded in step 1. To do this select the right device from the iTunes sidebar. Now press and hold left “alt” (option button) on the Mac (Left “Shift” button on Windows) on the keyboard and click on the “Restore” (Not “Update” or “Check for Update”) button in iTunes and release this button. This will cause iTuens to prompt you to select the firmware file. At this point you select the right ipsw file and click on “Open”.

Step 6:

You now have to be patient. Your iPhone screen at this point will be showing a progress bar indicating installation progress.

Between this process, iTunes might show the following error messages: “The iPhone could not be restored. An unknown error occurred (1004).” and “iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes.” Do not panic!

Press “OK” to continue. This is absolutely normal and there is no need to worry.

Step 7:

Your iPhone at this point will be stuck in Recovery Mode and show the “Connect to iTunes” screen. To exit your Recovery Mode, use TinyUmbrella or RecBoot utility.

In case you choose to run TinyUmbrella, just select “kick device out of recovery” button as shown above.

If you use RecBoot, you can just click on the “Exit Recovery Mode” button. Your iPhone will now reboot normally.

That’s it! You successfully downgraded to iOS 4.3 to iOS 4.2.1, 4.1, 4.02, 4.01 firmware. You can follow the normal guides to jailbreak firmware iOS 4.2.1, iOS 4.1, iOS 4.0.2 or 4.0.1.

As usual, stay tuned for more guides and how-to’s regarding your iOS devices by following us on Twitter and/or subscribing to our RSS feed.

Authors: _GadgetNews

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