Downgrade 3.1 to 3.0

Downgrade iPhone 3GS (OS 3.1 to OS 3.0) :

Jay Freeman (Saurik), from firmware 3.1 to firmware 3.0. This process will only work for those who have saved their SHSH to Cydia Server, for more on SHSH, read the complete detail blog post by Saurik here. Also to note here is that while this method will help you downgrade your firmware from 3.1 to 3.0, your baseband will not be downgraded which means you cant unlock it for now.

The following step-by-step guide will help you downgrade iPhone 3GS from firmware 3.1 to 3.0.

Step 1: Download iPhone firmware 3.0 for iPhone 3GS from here : iPhone2,1_3.0_7A341_Restore.ipsw

NOTE: Don’t use iPhone firmware 3.0.1 because Saurik’s Server currently does not have signatures for it.

Step 2: Download and install iTunes 9 if you haven’t already.

Step 3: Windows users Navigate to C:\Windows\System32\drivers\etc\ and locate “hosts” file.

Mac users can get to “/etc/” directory by going through “Go->Go to Folder” from Finder.

Step 4: Open this “hosts” file in Notepad (for Windows) or TextEdit (for Mac OS X) and add this

74.208.105.171 gs.apple.com

line as shown in the screenshot below:

Now simply save this file and you are good to go!

NOTE for Windows 7 and Vista: Start “Notepad” with Administrator privileges by right clicking on “Notepad” app, and click on “Run as Administrator“ option.

Step 5: Connect your iPhone to your computer and put it in DFU mode by: Hold down the power and home buttons for 10 seconds, letting go of the power button but continuing to hold home until iTunes recognizes the device with the message: "iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes.". At this point your iPhone screen should be entirely black.

Step 6: Start iTunes, press and hold shift key and then click on “Restore+SHIFT”.

browse to the firmware 3.0 .ipsw file you downloaded in Step 2 (it must be OS 3.0 build 7A341) and restore it. During the restore process, iTunes will throw you 1015 error which will say:

The iPhone “your iPhone” could not be restored. An unknown error occurred. (1015)

THIS IS IMPORTANT !!! : just ignore this error and restart the restoring process from Step 5 to Step 6 until you get the 1015 error again. At this point, simply ignore the error and close iTunes as your device has already been successfully downgraded to firmware 3.0.

Step 7: You can now jailbreak your iPhone which you have downgraded from firmware 3.1 to 3.0 by following the step-by-step jailbreaking guide here :http://mahmood1.com/jailbreak.aspx

Step 8 : Now you are ready to use the custom .ipsw files of 3.1 firmware to jailbreak iPhone 3GS go to here for jailbreaking iPhone 3GS OS 3.1 :http://mahmood1.com/iPhone3GS.aspx

Downgrade iPhone 3G (OS 3.1 to OS 3.0 or 3.0.1) : (source redmondpie)

The following step by step guide will help you downgrade your iPhone with firmware 3.1 to firmware 3.0.1. For those of you who upgraded to iPhone 3.1 may have found your device to be locked and un-jailbreakable as the tools forjailbreaking and unlocking are not out yet for iPhone OS 3.1. Fortunately, there is still a way to downgrade your phone from firmware 3.1 to 3.0.1. I have tried it on my iPhone 3G and it works perfectly on it. It should also work on the original iPhone (aka iPhone 2G). This method wont work on iPhone 3GS. Also to note here is that while this method will help you downgrade your firmware from 3.1 to 3.0.1, your baseband will not be downgraded which means you cant unlock it for now.

Step 1: Download and install iTunes 9 if you haven’t already.

Step 2: Download iPhone OS 3.0.1 firmware for your iPhone (3GS, 3G and 2G).

iPhone 3G

iPhone 2G

Step 3: Connect your iPhone with your computer and start iTunes, press and hold shift key and then restore hit ( Restore+SHIFT ) and then browse to the file you downloaded in step 2.

During the restore process, iTunes will throw you 1015 error which will say:
The iPhone “your iPhone” could not be restored. An unknown error occurred. (1015)
Just ignore this error and close iTunes.
Step 5: Start QuickPwn 2.2-1 (download QuickPwn2.2 here) and perform the procedure prompted to you by QuickPwn to reset your device to get out of error 1015:

Once your iPhone has restarted, close QuickPwn.

Step 6: Start iTunes again with the original AT&T SIM card. iTunes should now show the firmware version as either 3.0 or 3.0.1 depending on which ever firmware you chosed to downgrade to in Step 2.

Step 7: You can now jailbreak your iPhone which you have downgraded from firmware 3.1 to 3.0.1 by following the step-by-step jailbreaking guide go to here :

Step8: Jailbreak and unlock is now possible for iPhone 2G and iPhone 3G running firmware 3.1. Follow the complete step-by-step guide posted here in order to jailbreak and unlock your iPhone with firmware 3.1.

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