Apple decided to stop signing iOS 10.3.1 today, approximately a month later after iOS 10.3.2. You can no longer go back to the previous iOS firmware, meaning that users will no longer be able to migrate to iOS 10.3.1 and will instead stay on iOS 10.3.2.
After Apple releases a new iOS version, it almost always prevents the return of old iOS versions. This is caused by the desire of the users to have the latest iOS version of their users and their users to have the latest security and performance improvements. Those who are most affected by Apple’s application are undoubtedly Jailbreak users.
Apple released last month’s final version of the iOS 10.3.2 update. The update focuses on performance and security improvements under the hood while mainly addressing some mistakes. The Cupertino-based company is currently preparing to release iOS 10.3.3 and in this context continues to run tests with developers and members of the Apple Beta Software Program. Most likely, the final version of iOS 10.3.3 will be released publicly.
In summary, if you’re transitioning to iOS 10.3.2, you’ll have to stay in that version until the day Apple releases iOS 10.3.3.