It is no longer possible to downgrade iOS 8 to iOS 7.1.2 since Apple doesn’t sign iOS 7.1.2 any more. Users who are jailbroken and are still on iOS 7.1.2 but really need to restore their iPhone can lose the jailbreak if they restore via iTunes because this program will make them automatically install iOS 8 on jailbroken device which is now the most recent operating system.
There is no iOS 8 jailbreak yet. Such if you need to restore iPhone and not lose jailbreak iOS 7.1.2, you should use the special program to do so and succeed. Follow this instruction and do as you are advised to preserve the jailbreak on your smartphone.
How to Restore iPhone and Not Lose Jailbreak for iOS 7.1.2
Firstly, remember that you cannot launch Settings and erase your information because this will not help you. You will get a bootloop issue and have to restore the handset to its factory settings which means the end of jailbreak until hackers release it for iOS 8, 8.0.1, 8.0.2 and future 8.1.
Secondly, remember these two names: iLEX RAT and SemiRestore. These are tools that can help you restore iPhone to iOS 7.1.2 and preserve the jailbreak.
Restore iOS 7.1.2 Jailbreak with SemiRestore
Step 1. Download SemiRestore on your PC [this program is available to Windows and Linus users].
Step 2. Plug your iPhone to your computer.
Step 3. Install OpenSSH on your iPhone and without it SemiRestore won’t see your device. You can download this program on Cydia.
Step 4. Launch SemiRestore application and press Restore option.
Step 5. Once your device is restored it will reboot and you will see that you are still jailbroken even though you are restored to factory settings.
Restore iOS 7.1.2 Jailbreak with iLEX RAT
Step 1. Launch Cydia and search for iLEX R.A.T. application [it is available at http://cydia.myrepospace.com/ilexinfo/ which you should add to your Source list]. You should download it on your smartphone.
Step 2. Install the app and launch it.
Step 3. Choose iLEX RESTORE option and agree “yes” to start the procedure.
Step 4. After your handset reboots you will have to follow the Setup assistant. Make sure Cydia is still on your home screen and enjoy being restored while still remaining jailbroken.