Not long ago, I received a 1015 error message stating I could not upgrade, downgrade nor restore my iPhone 3GS (I am sure this fix will work for other models). This was because, I tried to upgrade my iPhone while it was Jailbroken. This is a new bug that has appeared. I know this because I done 8 hours Googling, forum searching everything about and of the problem, nothing helpful was found. But except a few useful posts about the apps: iReb, Redsn0w, sn0wbreeze & TinyUmbrella. If this is your problem, you need to follow these steps.
Note: Date may vary and versions may be newer. This is strictly for the current iOS 4 firmwares. In-case this may not work, try downloading all the firmwares in the iOS 4 and then trying the steps below.
- You firstly need to download the following (exact versions):
• iREB 4.0.x-4.1-RC2
• redsn0w 0.9.6b4
If your asking for the download links, just bloody Google them.
- Firstly, download your last known firmware (4.1 for the newer 3GS's) (Google "ipsw" for this)
- Extract all of them to your Desktop or into 1 folder of your choice.
- Run sn0wbreeze and use the firmware (4.1) you just downloaded. Use simple mode and it will then drag a new type of ipsw to your folder or desktop. Once thats done, run through iReb if sn0wbreeze hasn't done that yet for you.
- Close iTunes. Open up TinyUmbrella and hit, Run TSS Server.
- Open up your host file in your C:\Windows\System32\Drivers\etc\ and double check, at the end, there's something called 127.0.0.1 gs.apple.com. If there is your good to go.
- Open iTunes and hold down control and click the Restore button.
- Open the one custom-ipsw that sn0wbreeze created for you in step 4 and let it do the magic.
- Once it's done, it should give you a black screen on your iPhone.
- Final step is to run redsn0w and open the FIRMWARE YOU DOWNLOADED, not the custom one and boot in tethered.