Apple is no longer signing iOS 15.4 for the iPhone
(iMore iPhone)

What you need to know Apple has stopped signing iOS 15.4 after releasing a newer version of the software. Users are now unable to install iOS 15.4 on their iPhones. The only version of iOS that is now available to be installed is iOS 15.4.1. It`s time to let old OS die. Apple has stopped signing iOS 15.4, meaning that it is now blocking downgrades to that version of iOS on the iPhone. This means that anyone who wants to install a version of iOS must now install iOS 15.4.1. Apple is known to stop signing older versions of iOS as it releases newer versions in order to make sure that users are running the latest version of Apple`s software for the iPhone. Newer versions of each software not only include new features and bug fixes but performance improvements and security updates as well. Now, anyone who attempts to restore an iPhone will have only iOS 15.4.1 as Apple is now blocking downgrades to iOS 15.4. Those who are on the developer and public beta train can, of course, sti...