Okay guys, I seen many of you have problems downgrading such as Error 3194 (i got this as well) so i decided to write a guide. I have successfully downgraded from iOS 4.0 to 3.1.3 but first of all you need your SHSH blobs on file meaning its on your computer OR saurik's Cydia Server This downgrading method only applies to 3rd Generation iPod Touches and iPhone 3GS! For OTHER devices, please refer to page 3, post #27! Thanks! Apple has already stopped signing 3.1.2 firmware and soon they are going to stop signing 3.1.3 (already stopped signing in some reports)to prevent jailbreakers from downgrading. So this guide is on how to bypass that. Step 1 Download Umbrella and this TinyTSS Quick Starter Links to Umbrella UPDATED! (as of July 8th 2010) Step 2 Now, use WinRAR to extract Umbrella to a folder (using the right-click Extract to option). Let's rename the folder to "Umbrella" for easier access. Then, extract the 2nd file TinyTSS Quick to your desktop. You should be getting one folder and a .bat file. Step 3 Now, launch My Computer and navigate to C:\WINDOWS\system32\drivers\etc (this is on a PC with XP) In this folder you should see a file name hosts. Okay, now launch Notepad from All Programs > Accessories and drag the hosts file into the notepad. Step 4 Now add these few lines to the bottom of the file "IF SHSH IS ON PC!" "IF SHSH IS ON CYDIA!" What you are doing here is that you are tricking iTunes that it is contacting Apple, but it is actually contacting your computer or Cydia (depends where your SHSH file is) And I put all of Apple's servers because gs.apple.com ONLY did not work in my case, so I entered all. You should get something like this. (My SHSH file was on my PC) If your SHSH file is on PC, go to Step 5, if it is on Cydia skip to Step 7. Step 5 Now IF your SHSH file is on your PC, get it and paste it in the Umbrella folder you extracted earlier on. For easier description, we are going to rename it "ecid.shsh" without the quotes. This is how it should look like. Step 6 Next, launch the TinyTSS Quick.bat file. It will first prompt you for the location of TinyTSS.exe. In my case it was C:\Documents and Settings\User\Desktop\Umbrella. Next, it will ask for the name of your SHSH file, REMEMBER WE RENAMED IT TO ecid.shsh? Enter that, WITH the .shsh Now you should end up with a line saying "Starting TinyTSS Server on port 80". This is normal. LEAVE THIS CMD PROMPT OPEN WHILE RESTORING! DO NOT CLOSE IT! Step 7 Now, put you iDevice into DFU Mode. Those who do not know how to, i've provided a guide from a reliable source. How to put iDevices into DFU Mode - iClarified If you followed the guide completely, meaning you launched iTunes first and did the steps ending up with a blank screen, iTunes should say it detects an iPhone/iPod in recovery mode. ENSURE your iDevice screen is BLANK and not with a iTunes logo and a USB cable (which is Recovery Mode). If you have the iTunes logo, do the steps to put it in DFU mode again. Step 8 Now, get ready an ipsw of 3.1.3 or 3.1.2 (this depends on what firmware you backed up your SHSH on, if you backed it up on 3.1.2 you can only downgrade to that FW version) I cannot provide links of the ipsws as it is against the forum rules. Now, hold Shift on your keyboard and click the Restore button. Select the ipsw that you have and now iTunes should do the rest. Now, the TinyTSS Quick CMD Prompt should be listing a lot of text, ignore this, its just doing its job. Step 9 Once the restore is complete, you can safely close the TinyTSS Quick CMD Prompt (it should say "successfully written blob response" or something like that). Then, go back to C:\WINDOWS\system32\drivers\etc and open up the hosts file with notepad AGAIN. Erase all the entries you entered earlier as this will make iTunes Store not work and many iTunes functions may be broken, SO IT IS IMPORTANT TO ERASE THE ENTRIES! Step 10 CONGRATULATIONS! You have successfully downgraded! Here are some quick links for jailbreaking. Blackra1n Spirit This guide was written by purely by me, with the help of tips from this wonderful community. I would like to extend my gratitude and thanks to the user SeaJay (formerly known as ownerofspam) for providing us with the links for Umbrella and the TinyTSS Quick.bat file! If you have any comments or problems, please let me know and I will help you to the best of my ability! Thanks again! P.S Thanks @studangerous for stickying this!