Apple released developers preview of iPhone OS 4.0 beta yesterday with many exciting features like Multitasking, Game Center, Folder Feature and support for 5x Digital Zoom. As this build of iPhone OS 4.0 is beta, so you may experience some bugs while using it on your iPhone or iPod Touch. Incase you want to revert back your iPhone OS 4.O to iPhone OS 3.1.3 then follow the step by step guide below. Please note that this procedure will only downgrade your firmware from 4.0 to 3.1.3. Your baseband 05.13.03 (still unhacked) will remain unaffected. Don't use this guide to downgrade from 4.0 to 3.0.1 as Saurik Server do not have any signatures for firmware 3.0.1. If you have saved your SHSH to Cydia Server, then follow the guide below.
Steps Edit HOSTS File In Windows And Mac
For Windows Users:
*iPhone 3G and iPod Touch 2G (non-MC) users do not need to edit their Windows HOSTS file!
- 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:
*iPhone 3G and iPod Touch 2G (non-MC) users do not need to edit their Mac HOSTS file!
- 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.
Steps To Downgrade iPhone OS 4.0 To iPhone OS 3.1.3
- Disconnect any cable or dock attached to your device and turn it completely off.
- Now hold down the home button and while holding it, connect your device to your PC / Mac via cable or dock.
- Don't release home button unless you see a dock cable pointing to the iTunes icon.
- Now you are in recovery mode. Now launch iTunes if you haven't already.
- iTunes will detect your iPhone in recovery mode as shown in the screenshot below.
- Windows users: Press Shift+Restore button to select iPhone OS 3.1.3 IPSW file.
- Mac users: Press Option+Restore button to select iPhone OS 3.1.3 IPSW file.
Incase your encounter error messages with code 1011, 1013 or 1015, simply ignore these but if you encounter error messages with code 1601, 1602 or 1600, then try putting your iPhone in DFU mode again. You can look for a fix here.
Update1: Downgrade iPhone Firmware 4.0 Beta To Firmware 3.1.2
Update2: Downgrade Firmware 4.0 Beta To Firmware 3.1.3 On Mac
Update3: Downgrade iPhone Firmware 4.0 Beta To Firmware 3.1.3 On Windows
Update4: Downgrade iOS 4.0 to iPhone OS 3.1.3 | Windows & Mac
You can go through our step-wise tutorials on jailbreaking iPhone 2G/3G/3GS and iPhone Touch 1G/2G on firmware 3.1.3 using redsn0w 0.9.4, sn0wbreeze, PwnageTool 3.1.5. Unlocking can be done using ultrasn0w or blacksn0w.Contact Us for News Tips, Corrections and Feedback