Restore iPhone 3GS to 3.1.2 - MAC

This guide will teach you how to restore your iPhone 3GS to 3.1.2 instead of 3.1.3 using the SHSH details stored on Cydia for your 3GS (MAC ONLY).

This method also works to restore iPhone 3GS devices to 3.1.2 instead of 3.1.3 for many that have encountered an error with sn0wbreeze (as long as you haven't already  done a normal restore to 3.1.3 via iTunes).

If you have already restored on stock Apple firmware 3.1.3 via iTunes this guide may leave your phone unable to connect to the network (the 3.1.3 baseband and 3.1.2 firmware may not work well together). If that turns out to be the case the solution would be upgrading back to 3.1.3.

The first requirement is that Cydia has your SHSH details stored for 3.1.2. If you have opened Cydia and seen green text at the top "This device has SHSHs on file for iPhone OS: 3.1.2" then you can restore to 3.1.2.

You need to edit your host file to connect to Saurik's server instead of Apples to sign the 3.1.2 firmware when you restore.

Follow the guide below -

1.) Download OS 3.1.2 for iPhone 3GS (Direct Download Link)

2.) Next look in your Apple Menu and find Go.

3.) Click on Go to Folder.

 

4.) Enter in /etc/ and click Go

 

.5.) Find the hosts file.

6.) Open the file with TextEditor

7.) Add "74.208.10.249 gs.apple.com" at the end of the file.

8.) Click Save.

9.) Before continuing enter restore mode.

One way to do this is disconnect your phone from the computer and turn your phone off. Start iTunes. Hold the home button on your phone and plug it in. Continue holding the home button until iTunes indicates you are in restore mode.

10.) Launch iTunes, and hold the option key while you click Restore.

11.) iTunes will go through the restore process and your device will be back on 3.1.2.