In the flurry of upgrades and jailbreak tools, many may have come to the  realization that they are not yet ready for iOS 4 for various reasons,  wether it be a new bootrom, or you simply miss your Jailbroken apps from  Cydia, this guide will help you downgrade your recent update to iOS 4  back to 3.1.x. While it is highly recommended to  restore to 3.1.2, some of you may not have that option, but only  use 3.1.3 as a last resort. However, it is important to note that if  you are downgrading, in order to upgrade to iOS 4 JB, you MUST be on  3.1.2. The only jailbreak for 3.1.3 is Spirit, which is NOT compatible  for upgrading to iOS 4 Jailbroken. 
Before we even get started, you must have your SHSH blobs on file with  Saurik's server. You can tell if you have this by opening cydia and  seeing a message similar to this:
If you are 100% sure you have this message, and recall choosing the  "Make My Life Easier" option when you first launched Cydia, then it's  time to proceed. If you unfortunately do not have these saved, and are  already on iOS 4, then there is nothing you can do. 
Ok, so you made it past the hump. You have SHSH blobs on file via Saurik's Cydia server, which means your going to be able to downgrade just fine. The next question is, which firmware would you like to downgrade to. In my case, I don't have SHSH blobs on file for 3.1.2, so I will be downgrading to 3.1.3 instead.
Grab your stock firmware from the links provided at the end of this thread. Make sure you are using the one you have SHSH blobs on file for.
Now that we've got this far, its time to begin:
Note: This guide ONLY applies to the 3GS
Step 1: Modify the Hosts file
In order to trick iTunes into connecting to Saurik's server instead of Apple, we need to modify the hosts files. This applies to both Windows and Mac users. By doing this, we are able to get iTunes to think that our device is eligible for a downgrade. Normally when a new firmware is released, the older firmwares are no longer signed by Apple, thus preventing downgrading, but by connecting to Saurik's server, we bypass this issue.
Ok, so you made it past the hump. You have SHSH blobs on file via Saurik's Cydia server, which means your going to be able to downgrade just fine. The next question is, which firmware would you like to downgrade to. In my case, I don't have SHSH blobs on file for 3.1.2, so I will be downgrading to 3.1.3 instead.
Grab your stock firmware from the links provided at the end of this thread. Make sure you are using the one you have SHSH blobs on file for.
Now that we've got this far, its time to begin:
Note: This guide ONLY applies to the 3GS
Step 1: Modify the Hosts file
In order to trick iTunes into connecting to Saurik's server instead of Apple, we need to modify the hosts files. This applies to both Windows and Mac users. By doing this, we are able to get iTunes to think that our device is eligible for a downgrade. Normally when a new firmware is released, the older firmwares are no longer signed by Apple, thus preventing downgrading, but by connecting to Saurik's server, we bypass this issue.
1a: Modifying Windows Hosts file
Browse to Windows\System32\drivers\etc\. Inside this directory you  should be able to find a file named "Hosts". Open this in Notepad and  add the following line to the bottom.
74.208.10.249 gs.apple.com
Due to some restrictions on Windows you may have to create a copy of  this file on your desktop and then drag and drop it to replace. 
1b: Modifying Mac Hosts File
The same idea as windows here, only in a different location. On your  Mac, Open Finder, and choose Go from the toolbar, and then Go To Folder.  Type in the following: etc/.
This folder should pop up, and inside you'll see the hosts file. Open this file with textedit and add the following line to the bottom.
74.208.10.249 gs.apple.com
Save the file.
2: Install Firmware Manually
Now you can launch iTunes, shift click, or ctrl click, Restore, choose  your firmware, and the downgrade begins. Some of you may not have any  problems from here, but some of you will end up in recovery mode by the  end of it. Do not worry, this is normal. Now we just need to force the  phone out of recovery mode. 
3: Fix Recovery Boot Loop
In our case, I used iReb to easily fix the recovery boot method. This is  of course on Windows, but you can also use many of the methods out  there to fix the recovery loop. If you need further help with this, post  a reply.  
4: Welcome Back to 3.1.x. 
Your back. Now you can patiently wait for further development on iOS 4  in the meantime and have all your fun apps back. Hope this helps  everyone. I Will add photos shortly. 
Resources & Links: 
We have had guides for downgrading the 3GS to 3.1.2  for awhile now check em out if you need more instruction
Downgrade 3GS to 3.1.2 on a MacDowngrade 3GS to 3.1.2 on Windows
3.1.2 Firmware (Official Apple Links)
3.1.3 Firmware (Official Apple Links) -  Only use these if you do not have 3.1.2 on file.
Utilities
iReb for Windows (Mac Soon)








Comments
Post a Comment