Hello guys, I am getting “Not a Valid IPSW” every time I try to create a custom iOS 4.3.3 firmware using Sn0wbreeze, so that I could downgrade my iPhone 3GS back to iOS 4.3.3. I am pretty sure that I have the right firmware for my device as I have downloaded it from a reliable source. Thanks.
Asked by: Simon from Grand Prairie, Texas
If Sn0wbreeze is still throwing Invalid IPSW error, then you could download Marxio File Checksum Verifier from here and check MD5 and SHA1 checksums of the downloaded IPSW. You could also use TheiPhoneWiki website to check the correct checksum values of your IPSW file. If you get different checksum values form the downloaded IPSW file into the firmware file listed on the website then re-download the fresh IPSW for your iPhone from this website or from iClarified. That’s it! Hope this helps.