restore downgadee ios 4.3.1 to 4.2.1

[Mimi Kebabu]

I'm trying to downgrade my iphone 3gs 4.3.1 to 4.2.1.
I did all steps correctly, but I cannot find 4.2.1 on itune when i restore it.
I have it on my desktop as zip file, but it does no show up when I open custome restore on itune.

Please help me to restore downgraded ios.

 

[Applejuiced]

You have to download it as a .ipsw file, not zip.

 

[iPhone Addict]

You can find official IPSWs for Apple firmware from iclarified.com.

 

[Mimi Kebabu]

Thank you for asnwering my question.

Everytime I tried to download it, it was automatically downdoaled as zip file.
How I can downloaded as ipsw?
Is there anyway to change zip to ipsw?

 

[Applejuiced]

Thank you for asnwering my question.

Everytime I tried to download it, it was automatically downdoaled as zip file.
How I can downloaded as ipsw?
Is there anyway to change zip to ipsw?

Change the extension before you download it from .zip to .ipsw
Then on the drop down Save as type: all files
And click save.