Yesterday Apple released iOS 8.1.1 to the public which kills iOS 8 untethered jailbreak. So if you accidentally upgraded your iPhone, iPad or iPod Touch to iOS 8.1.1 and want to downgrade back to iOS 8.1, then the good news is that you still have the chance to do this as long as Apple still signing iOS 8.1. However, you should hurry up before Apple stop signing iOS 8.1..
Important Notes to read:
Doing this you will be only downgraded to iOS 8.1
You'll be able to downgrade your device as long as Apple singing iOS 8.1 firmware.
Make sure to backup your device before restoring or downgrading via iTunes.
Apple doesn’t recommend downgrading so please proceed at your own risk.
So let's start:
STEP 1: Backup your iPhone via iTunes before downgrading your device to iOS 8.1
STEP 2: Download iOS 8.1 firmware file for your iPhone/iPad or iPod Touch.
STEP 3: Now connect your iPhone running on iOS 8.1.1 to the PC/Mac.
STEP 4: Launch iTunes and select the iOS device from the top right corner, to the left of the iTunes Store button.
STEP 5: Hold the Alt/Option key on the Mac or Shift Key in Windows on your keyboard and click on the Check for Update option, instead of restoring. We were able to successfully downgrade from iOS 8.1.1 to iOS 8.1 using this step, but if you want to go by the book then you should use the Restore method, but it will be more time consuming. Important note: If you use the Restore method, then it will wipe the data from your device so please don’t forget to take a backup.
STEP 6: Now simply select the ipsw file that you have downloaded above..
STEP 7: Now iTunes will inform you that you are about to upgrade to iOS 8.1, click on 'Update'.
STEP 8: iTunes now should start downgrading to iOS 8.1, so wait a few minutes until it finishes..
That's it, you are done bro ! If you have encountered any problems while following the above guide, please let us know in our comment section below...