Downgrading from 4.2.1

[SlackR]

Hi guys, I'm having a hard time doing downgrading from 4.2.1 to 4.0.1. I've tried downgrading from 4.1.1 but failed and restored but needed to upgrade to 4.2.1 as apps like tinyumbrella could not kick my device out of recovery mode. Could someone guide me along the steps to downgrading?

Thanks!
SlackR.

[Simon]

I assume you have the SHSH required to downgrade right?

[i.Annie]

If you can't downgrade because you might not have SHSHs to do it, you'll need a custom firmware.

Edit: if it isn't an iPhone 4

[SlackR]

Hi all, I am using iPhone 3GS. Yes, I do not have SHSH. How do I downgrade with the custom firmware?

Thanks!
SlackR.

[Simon]

If you don't have shsh then you cannot downgrade.

[SlackR]

Can I download the SHSH in order to downgrade?

[i.Annie]

No SHSHs are unique to each device

[SlackR]

How about custom firmware?

[i.Annie]

SHSHs are required for custom fw as well

[matiasv]

Hi;
I have a 3gs and I have my shsh, where can I find the tutorial to downgrade.

Thanks

[i.Annie]

Just download a stock firmware you want to downgrade to. Download TinyUmbrella. Run the TSS server in TinyUmbrella, and shift+restore to the stock firmware you want to downgrade with.

[Simon]

Step by step guide if you need one: [How-To] Using tiny umbrella to update/downgrade/restore

[aamodr]

can one downgrade to a custom firmware? i need to preserve the baseband for unlock.

[Simon]

Downgrade? Normally people look to preserve baseband when updating.

[i.Annie]

Downgrading does not change your bb.

But you can very well downgrade with a custom fw if you wish, so long as you have SHSHs for it.