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  • [Guide] How To Downgrade iOS 4 : iPhone 3GS

    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.
    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. 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. 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 Mac
    Downgrade 3GS to 3.1.2 on Windows

    3.1.2 Firmware (Official Apple Links)
    Download iPhone OS 3.1.2 for iPhone 2G
    Download iPhone OS 3.1.2 for iPhone 3G
    Download iPhone OS 3.1.2 for iPhone 3GS

    3.1.3 Firmware (Official Apple Links) - Only use these if you do not have 3.1.2 on file.
    Download iPhone 3.1.3 firmware for iPhone 2G
    Download iPhone 3.1.3 firmware for iPhone 3G
    Download iPhone 3.1.3 firmware for iPhone 3GS

    iReb for Windows (Mac Soon)
    iRecovery (Mac & windows)
    This article was originally published in forum thread: [Guide] How To Downgrade iOS 4 started by nickhesson View original post
    Comments 174 Comments
    1. thazsar's Avatar
      thazsar -
      Is anybody with iOS4 willing to try something? Proswitcher is now working for iPad and I was wondering if it will work for iOS4. It is still in beta but the repo is: add rpetri.ch repo

      please let me/us know if this works. Thanx!!!

      did u try it with this new repo? I know the old repo didn't work but maybe...just maybe...this will work! Thanx for trying!
    1. aaron0043's Avatar
      aaron0043 -
      i have an ipod touch and a 3gs, can i still make the SHSH-save part with my touch and use it for my iphone?
    1. 24inthelead's Avatar
      24inthelead -
      I have 3G, 4.0, Jailbroken with redsn0w:

      I cannot get this to happen

      I got as far as getting it to 3.1.3,
      blaickrai1n wouldnt work
      took it to a diff pc, blackra1n worked, but then
      I had no at&t service, so I had to restore it again back to 4.0

      NOTHING, is working for me

      I had 3.1.3 jailbroken, upgraded to 4.0
      jailbroke and now I cannot get back to 3.1.3, or 3.1.2.

      what gives?
    1. snowdweller's Avatar
      snowdweller -
      Very nice
    1. jhonycovers's Avatar
      jhonycovers -
      been looking for this for a while thanks
    1. 24inthelead's Avatar
      24inthelead -
      anyone know what to to for just 3G?
    1. BennyPR's Avatar
      BennyPR -
      Check the first post.

      Quote Originally Posted by olivo42 View Post
      how can i get a custom FW 3.1.2?
      Olivo check the first post here.
    1. cuzz501's Avatar
      cuzz501 -
      I did click make my life easier, then broke my screen, got a new phone with 4.0.2 tried to downgrade to 4.0.1 and got several different error messages in iTunes. My question is, am I able to get my shsh blobs from Cydia if it was for a different device? or are the shsh blobs device specific?
    1. vantheman169's Avatar
      vantheman169 -
      Shsh blobs are device specific, that's what sux about getting a warranty replacements
    1. NiGHTsC's Avatar
      NiGHTsC -
      Anyone who's kind and smart and pro enough, please tell me that my 3G will not lose anything for downgrading iOS4.0.1 to 3.1.2, cause my latest 3.1.2 backup is a year old and lots of things changed during this year...

      Thank you.
    1. thazsar's Avatar
      thazsar -
      If u downgrade, you can only restore from that 3.1.2 backup. The new iTunes will not let you restore a 4.x device back to 3.x so you have to have an old backup to use.
    1. natim's Avatar
      natim -
      Don't know near as much as most of you here but could he get an older version of itunes and make it happen?
    1. NiGHTsC's Avatar
      NiGHTsC -
      Quote Originally Posted by thazsar View Post
      If u downgrade, you can only restore from that 3.1.2 backup. The new iTunes will not let you restore a 4.x device back to 3.x so you have to have an old backup to use.
      What will I lose after downgrade? everything? all of infos? like an empty iPhone?
    1. thazsar's Avatar
      thazsar -
      To downgrade, he will HAVE to have an older version of itunes (i think 9.0 maybe or 9.1.1 at the latest) to downgrade.

      Unfortunately, an earlier iTunes has no effect on the downgrade process as a whole: the 4.0 upgrade required us to upgrade iTunes to 9.2 (or something like that). So, (i think) you can't downgrade to 3.1.2 with iTunes 9.2 & you can't install 4.x without iTunes 9.2.

      Also, when we sync, we usually let iTunes backup our phones automatically before and after we upgrade FW. The down side to this is when you downgrade (using iTunes 9.1.x) and then try to restore your previous info, it will not let you restore since your recently saved Backup is for 4.x not 3.x!!! Basically, ur stuck UNLESS you saved/moved your BEFORE backup somewhere else OR you stopped iTunes from BACKUP after the FW upgrade.

      Hope that makes sense!