Avid iOS jailbreakers are in for some bitter news as Apple has just closed its signing window for the iOS 9.0.2 firmware. Consequently, you can no longer downgrade from iOS 9.1 to the previous jailbreakable firmware, iOS 9.0.2.
If you are still sceptic, check the real-time signing status for your device's iOS firmware by visiting the website, ipsw.me. If you see a green tick against the firmware file, it means Apple is still signing it and a red warning sign against the firmware file, suggests that the company has stopped signing it, reports iPhone Hacks.
Apple has patched up two key exploits used in Pangu 9 jailbreak with the release of iOS 9.1, which renders the existing Pangu jailbreak useless. The inability to jailbreak iOS 9.1 coupled with the closure of the signing window for iOS 9.0.2, suggests that you can no longer downgrade to a jailbreakable iOS version or install jailbreak tweaks, unless you evade the upgrade.
With Pangu team not divulging anything about the jailbreak status for iOS 9.1 and 9.2; it is a safe bet to postpone your upgrade plans, especially if your device is already jailbroken.
Jailbreakers are advised to exercise caution while installing new jailbreak tweaks, as a broken or incompatible tweak could easily corrupt the software and force a firmware restore on the device. Consequently, you will lose the jailbreak as well as installed apps and tweaks on the device.