Nearly three weeks after releasing iOS 9.3.4, Apple has stopped signing iOS 9.3.2 and iOS 9.3.3 for compatible iPhone, iPad, and iPod touch models, making it impossible to downgrade from the latest firmware version available to these older ones.
iOS 9.3.2, initially released to the public on May 16, 2016, was an update that initially bricked some 9.7-inch iPad Pro devices until an updated version was released on June 2.
iOS 9.3.2 was followed by iOS 9.3.3, released on July 18, and iOS 9.3.4, released on August 4. iOS 9.3.2 and iOS 9.3.3 were both compatible with the recent Pangu iOS jailbreak software, which is disabled by iOS 9.3.4.
Jailbreak users are accustomed to this process which lets them temporarily downgrade from the latest software version available to the previous one. Apple typically leaves a two-week window between the time the latest software is released and the time the previous one stops being signed.
For most users, this doesn’t really have any impact on the usage of their devices. However, for jailbreak users, this means that they should be extra careful not to accidentally update their devices to iOS 9.3.4, as there is now no going back.
At this time, beyond the usual round of fakes floating around, there is no way to jailbreak iOS 9.3.4. iOS hacker Luca Todesco recently showed off a jailbroken iPhone running iOS 9.3.4, but it is very unlikely this will be released to the public.