If you have upgraded to iOS 4.1 beta 1 and now want to downgrade to iOS 4.0 or 4.0.1, then follow the step-by-step guide below which will enable all iPhone 4, iPhone 3GS & iPhone 3G and iPod Touch 2G (MC, non-MC) & 3G users to downgrade their iDevice's firmware from iOS 4.1 to iOS 4.0 or 4.0.1. If you have upgraded to iOS 4.1 beta 2 (Jailbreakable) then you might not be able to unlock your device due to baseband upgradation.
Before continuing, make sure your have SHSH blobs saved for either iOS 4.0 or iOS 4.0.1 (both are same) for iPhone 4, 3G, 3GS and iPod Touch 2G, 3G. We have already explained in detail that why and how you can save SHSH blobs for iOS 4.0 / 4.0.1 for iPhone 3G and iPod Touch 2G.
Downgrade iOS 4.1 to iOS 4.0 / 4.0.1 on Windows & Mac
*Find all required download links at the end of post
- *If you want to downgrade your device from iOS 4.1 to iOS 4.0 then download the iOS 4.0 IPSW file respective to your device. If you want to downgrade your device from iOS 4.1 to iOS 4.0.1 then download iOS 4.0.1 IPSW file. After downloading the firmware file, place it on your desktop.
- Put your iPhone in DFU mode. Follow the steps below to put your iPhone into DFU mode:
- Start iTunes. Connect your device to your PC / Mac with the USB cable.
- Turn of your device completely.
- Now hold down the Home and Power button for exactly 10 seconds and after that release the Power button but keep holding the Home button until iTunes detect your iPhone / iPod Touch in recovery mode. Your iPhone or iPod's screen should be totally blank at this point.
For Windows Users:
- Navigate to Start->All Programs->Accessories and then right click on the Notepad icon and choose Run as Administrator
- Now go to File menu in opened Notepad and choose Open or simply press Ctrl+O. Browse to C:\Windows\System32\drivers\etc and open HOSTS file.
- Once HOSTS file is opened, copy-paste the following line at the end of file as shown in the screenshot below
- Now again go to File menu and choose Save or press Ctrl+S.
For Mac Users:
- Click Go->Go to Folder and then enter path /etc
- Now open HOSTS file with TextEdit and add the following line with at the end of the file as shown in the screenshot below.
- Now go to File and choose Save As, uncheck If no extension is provide, use .txt and save the HOSTS file on your desktop.
- Now replace the original HOSTS file with the one you just saved on your desktop. Incase you are prompted for the password, just enter it and click OK.
TIP: If iTunes throw error 1015 during the restore process, use the instructions here to fix the error.
Once you have downgraded to iOS 4.0 or iOS 4.0.1, use the following tutorials to jailbreak and unlock your device:
Download iOS 4 for iPhone 4/3GS/3G, iPod Touch 2G/3G – Final Version
Download iOS 4.0.1 for iPhone 4, iPhone 3GS and iPhone 3G
Download iTunes 9.2.1 for Windows and Mac
Download Recboot for Windows and Mac