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I'll do the upgrade from ios 4.1 jailbreaked (on an iphone 3g with a foreign locked sim) without updating the baseband. My baseband is 05.14.02 (bootloader 5.9). So I should to obtain an iphone 3g ios 4.2.1 jailbreaked with the 05.14.02 baseband (I'm not interested to use it for phone calls).

I would to know what I have to save before the upgrade to revert to the original state (ios 4.1 jailbreaked) in case of failure.

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1 Answer 1

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You need to save the SHSH blobs for your phone.

This can be done by:

  1. Allowing Cydia to save them for you automatically.
  2. Using TinyUmbrella to back up the blobs to your computer.
  3. Install iSHSHit from Cydia, which can access your SHSH blobs, save them on your phone, and send them as email attachments.

Currently Apple is blocking access from Cydia to the servers that give the SHSH blobs out, so options #2 and #3 are left.

Finally, Apple is no longer signing for 4.1, so unless you already backed up SHSH blobs somehow, you will not be able to downgrade.

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"Finally, Apple is no longer signing for 4.1, so unless you already backed up SHSH blobs somehow, you will not be able to downgrade". Is this true also if the baseband remains 05.14.02 or only when it is updating to 06.15? –  Fran Apr 22 '11 at 15:58
    
Baseband version has nothing to do with downgrading. This is solely determined by the iOS version of the device and if Apple is still signing for the version on that hardware. Once they are no longer singing, there's no way to downgrade unless you backed up the SHSH blob. –  mindless.panda Apr 25 '11 at 21:11

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