Downgrade iOS 4.2 to iOS 4.1, 4.0.2, 4.0.1 for iPhone 4, 3GS, 3G And iPad

This is a guide to downgrade iOS 4.2 to iOS 4.1, 4.0.2, 4.0.1 for iPhone 4, 3GS, 3G and iPad in case you feel like downgrading to the older firmware versions. The reason is obvious you want the jailbreak and unlock ability back, since there is no jailbreaking tool available yet for the latest version of this iOS 4.2 plus it consists of new baseband, therefore there is no workaround available to unlock it even using the Ultrasn0w (at least currently).

So follow the following guide to downgrade your iOS firmware back to the iOS 4.0.1, 4.0.1 and iOS 4.1 if you have SHSH blobs saved:

1. Get the previous iOS first: for iOS 4.1 and for iOS 4.0.2 and below.

2. Set up your iPhone in recovery mode

3. This step only applies to iPhone 3GS, iPod touc 2G & 3G (MC model) and iPhone 4 that have SHSH Blobs saved on Cydia. Make sure you have SHSH files saved, or else there is no way to downgrade your iOS.

• For windows go to-> C:\Windows\System32\drivers\etc\ and locate "hosts" file.
• For Mac OS X navigate to "/etc/" directory by heading to "Go –> Go to Folder" from Finder.

Now you need to open and edit the file named Hosts, use your text editor like Notepad for Windows and TextEdit for Mac OS X, add the following to the Hosts file:

74.208.105.171 gs.apple.com

Just like this:

And then save it!

4. Now your iPhone need to be restored to the iOS you've downloaded at the first step. On the iTunes's sidebar click your phone icon, on your keyboard hold left "alt" (Mac) or left "shift" button for Windows" and continue it with click on "Restore" button inside iTunes, afterward release this button.

5. Do not nothing, but make some hot coffee at this stage, as this going to take sometimes for iTunes to installs the iOS you selected for your iDevice. In case you receive the 1004 or 1015 error message from iTunes, just ignore it, means you are on the right road as the firmware you picked already installed successfully.

6. Unfortunately you will likely be stucked in the Recovery Mode at this stage, giving you a message say: "Connect to iTunes". To solve the said problem, you can use a program called TinyUmbrella. Download TinyUmbrealla according your OS you use:

• For Mac
• For Windows.

7. Done. Now you can go to jailbreak and then unlock your iDevices:

• Jailbreak iPhone 3GS On iOS 4.1 using Pwnage Tool Unofficial Version
• Unlock iPhone 3GS On iOS 4.1 Old Bootrom Using UltraSn0w

Note: make sure you remove 74.208.105.171 gs.apple.com you added on the step 3, so you will be able to update to the upcoming firmware versions.

Via: RedmondPie.

Posted in: Downgrade