Today, Apple stopped signing two versions of its mobile operating system — iOS iOS 12.1.1 and 12.1.2. This means that now users can no longer revert to an older version of iOS.
It is worth noting that Apple constantly stops signing older versions of its mobile operating system. Typically after two or three weeks after the release of the new stable build. Such period is enough to allow users to test the new version of iOS and, if necessary, to revert back.
Thanks to this mechanism Apple has managed to contain the fragmentation of its mobile operating system, as well as to maintain a high level of security.
However, in some cases the inability to revert to older versions of iOS might allow users. For example, some iPhone and iPad users are forced to skip the updates, waiting for the release of the jailbreak. Otherwise, they simply will not be able to use it. In fact, now users who are still waiting for jailbreak iOS 12, you cannot upgrade to iOS 12.1.3, as in this version of cupertinos has already closed a number of critical vulnerabilities.