
Confirm that your iOS device version is 8.1.3 to 8.4
Check version via:
Settings - General - About - Version
Attention: if OTA device failed in Jailbreak, please download the latest firmware and flash it, then continue Jailbreak. Please backup your data before Jailbreak
Please use iTunes to backup your data in case of unnecessary lose.
Turn off passcode and "Find My iPhone" function Or Jailbreak will fail.
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