Apple has now officially stopped signing the previous versions of its mobile operating system, namely iOS 10.2.1 and iOS 10.3.
The announcement came just right after the company had released the second beta version of iOS 10.3.2.
Now that the older versions of iOS 10 are no longer valid, users who want to downgrade their iPhone's OS will no longer be able to do so. Downgrading will also no longer be possible even with the use of iTunes on a PC or Mac. Those who are already on iOS 10.3 and 10.3.1 are essentially stuck with the version they have.
According to the 9to5Mac, the main reason that Apple wants to prevent people from attempting to downgrade is that iOS 10.3 already changed the entire file system of the OS. Everyone who upgraded to iOS 10.3 had their devices upgraded to Apple's latest APFS file system. It might also be possible that downgrading to the 30-year old AFS+ file system would likely have problems during the transition.
As per Apple Insider, the newer APFS file system brings with it a lot of advantages and built-in features that aren't found on the archaic file system that Apple has been using since the first iPhone. Security protocols and better compatibility with solid state storage are already built into the file system, which means that Apple no longer has to embed additional codes on top.
iOS 10.3 also brought with it a number of security fixes that have patched several holes in the system. This also means that jailbreaking a device on iOS 10.3 and above will be quite difficult and may even be impossible as of the moment.
Those who still want to keep their jailbroken devices are not yet advised to update. However, those who want to have a more secure and a marginally faster operating system may upgrade their iPhones should they wish to do so. iOS 10.3 also adds a number of new features, including a Find My AirPods function, CarPlay updates, and a couple of animation changes.