Say a thread bellow about this, but know one answered it.

My iPhone 4 is on iso 5.0.1 and has been jailbroken with Redsn0w's tethered jailbreak.

So all I wanted to do is do a CLEAN restore to 5.0.1 and then re-jailbreak with Redsn0w's un-tethered jailbreak, and all I get is error 21 everytime I try to restore. No matter what computer or USB cord I use I get the same error code 21.

Both iTunes and Redsn0w are the most resent.

Any HELP would be Greatly Appericated.....

Several solutions were provided in the forum post below that should apply to you as well.

Either you're restoring a custom firmware and not a stock one (are you shift restoring? If so, where'd you get the .IPSW? Is it custom? Are you attempting to block a baseband update?) and you're not in Pwned DFU mode, or you have a line in your hosts file pointing to gs.apple.com, or you're having intermittent network issues.

In any case, more info would be helpful. Specifically, what iOS revision file you downloaded, where you got it, whether you're making a custom .IPSW to block the baseband, etc. If you've downloaded a stock .IPSW from Apple and haven't customized it, you'll want to check for network issues as well as they can prevent you from being able to receive the TSS response from iTunes.

Originally Posted by n1ckn4m3

Several solutions were provided in the forum post below that should apply to you as well.

Either you're restoring a custom firmware and not a stock one (are you shift restoring? If so, where'd you get the .IPSW? Is it custom? Are you attempting to block a baseband update?) and you're not in Pwned DFU mode, or you have a line in your hosts file pointing to gs.apple.com, or you're having intermittent network issues.

In any case, more info would be helpful. Specifically, what iOS revision file you downloaded, where you got it, whether you're making a custom .IPSW to block the baseband, etc. If you've downloaded a stock .IPSW from Apple and haven't customized it, you'll want to check for network issues as well as they can prevent you from being able to receive the TSS response from iTunes.

First off I'm not using or trying to use a custom firmware. I'm just tring to do CLEAN restore to 5.0.1 after jailbeaking with Redsn0w's tethered jailbreak. And then jailbreak again with Redsn0w's UN-tethered jailbreak.

I used iTunes to try to restore with there own ipsw. and also have downloaded iso 5.0.1 from iClarified and pointed iTunes to the ipsw with shift restore that I downloaded from iClarified and I get the same thing everytime error code 21.

Did you check your hosts file for any lines that point to gs.apple.com? Beyond that, I hate to say I don't know what to tell you. If you're using an OEM apple cable, you've tried other cables and other computers, other usb ports, etc., you don't have anything in your hosts file pointing to gs.apple.com, you're using a standard firmware and your iTunes passes all network and software diagnostic tests, I'm stumped...

Originally Posted by n1ckn4m3

Did you check your hosts file for any lines that point to gs.apple.com? Beyond that, I hate to say I don't know what to tell you. If you're using an OEM apple cable, you've tried other cables and other computers, other usb ports, etc., you don't have anything in your hosts file pointing to gs.apple.com, you're using a standard firmware and your iTunes passes all network and software diagnostic tests, I'm stumped...

How do I check if my host file is pointing to gs.apple.com?

Checked iTunes software diagnostic and it says NO iPhone found, but everthing else is working.

If you're on a PC, open C:\windows\system32\drivers\etc\hosts in a text editor and review the contents. If any line exists with gs.apple.com that doesn't start with "#", remove it.

Originally Posted by n1ckn4m3

If you're on a PC, open C:\windows\system32\drivers\etc\hosts in a text editor and review the contents. If any line exists with gs.apple.com that doesn't start with "#", remove it.

Found out what it was. Tinyunbrella was causing the problem. Un checked Set Host to Cydia on Exit and I was able to restore to iso 5.0.1.

Thanks for your help.

No problem, glad to hear it's taken care of!