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Thread: Option to downgrade 3GS 4.1 -> 3.1.2 (non-jailbroken)

  1. #1
    Question Option to downgrade 3GS 4.1 -> 3.1.2 (non-jailbroken)
    Hi,
    I've 3.1.2 iPhone 3GS (new bootrom) which isn't jailbroken. I've a few quick questions and I am unfamiliar with jailbreaking or downgrading.

    1) Which is the latest stable version (performance wise, I am not into much fancy looks)
    2) Is it possible to upgrade to non-latest version (e.g. 4.0.2)?

    3) If I upgrade to 4.x version, and then jailbreak it, would it be possible to downgrade back to 3.1.2 unjailbroken version as it was before?
    If so, what are pre-requisites? (all I know is to use the umbrella tool to backup shsh blobs of my non-jailbroken 3.1.2).

    4) Can I do this path to upgrade:
    3.1.2 (non-jailbroken) -> 4.x official -> jailbreak 4.x

    Thanks a lot!

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  3. #2
    Livin the iPhone Life
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    1. All firmware versions are stable and all jailbreaks are stable (except for sn0wbreeze maybe).

    2. Only with stored SHSHs. If you don't know what those are and haven't been jailbroken before, you likely don't have them so up- or downgrading to any version other than the current (4.1) is impossible.

    3. Depends. Do you have SHSH for 3.1.2? If yes, then yes. If no, then no.

    4. Depends. Do you have SHSH for 4.0/4.0.1? If yes, then yes. If no, then no.

    A note here, SHSHs aren't saved depending on which version is currently installed on your phone. They're only dependent on which firmware Apple is currently signing. What this means is that if you've never saved your 3.1.2 SHSH before, there's no way for you to get it now, even if you're on 3.1.2
    We're all just toymakers in the game of life.

  4. #3
    Thanks for replying. By stability I meant that some users have reported that certain 4.x versions slows down the phone.

    As of now I haven't saved any SHSH blobs. So my question is: Is there any way after upgrading to 4.1 to downgrade back to 3.1.2 (even if it includes complete reset/restoration that will erase all of my data).

    PS: Can you backup SHSH blobs from a non-jailbroken iPhone using umbrella or similar tool?
    Last edited by TheKing1; 2010-09-24 at 06:08 AM.

  5. #4
    No. If you do not have the 3.1.2 SHSHs then there is no path to downgrade.

    Even if you have 3.1.2 right now, you cannot backed it up as Apple has ceased signing the blobs. Apple only signs 4.1 right now and that is the only blobs that can be backed up or saved at the moment

  6. #5
    Thank you for your helpful replies. A slightly off-topic qs. I m thinking to jailbreak my current 3.1.2. Now I've learnt that to remove jailbreak later on, I need to "restore" it in iTunes n maybe then use backup.
    Now will restoring in iTunes automatically upgrade iOS to latest 4.1 or will it stay 3.1.2?

  7. #6
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    It will take you all the way to 4.1 ipsw, you cannot do any other version restore than restore to 4.1

  8. #7
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    Quote Originally Posted by TheKing1 View Post
    Thank you for your helpful replies. A slightly off-topic qs. I m thinking to jailbreak my current 3.1.2. Now I've learnt that to remove jailbreak later on, I need to "restore" it in iTunes n maybe then use backup.
    Now will restoring in iTunes automatically upgrade iOS to latest 4.1 or will it stay 3.1.2?
    How did you check which bootrom your phone has? 3.1.2 could be close to the edge between old and new.
    We're all just toymakers in the game of life.

  9. #8
    I checked my bootrom some months ago using some program (I can't remember which at the moment). But yea I am pretty sure that it's new bootrom.

  10. #9
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    Quote Originally Posted by TheKing1 View Post
    I checked my bootrom some months ago using some program (I can't remember which at the moment). But yea I am pretty sure that it's new bootrom.
    Alrighty. Was just making sure you hadn't been mistaken about that model mb/mc thing.
    We're all just toymakers in the game of life.

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