Apple today stopped signing iOS 17.1, a move that will prevent iPhone users from downgrading to that version of iOS. Apple is no longer signing iOS 17.1 following the release of iOS 17.1.1, which came out on November 7.
It is not unusual that iOS 17.1 is no longer being signed. Apple routinely stops signing older versions of iOS after new releases in order to encourage customers to keep their operating systems up to date and to prevent users from downgrading to older, less secure versions of the software.
iOS 17.1.1 is the current version of iOS 17 that is available to the public. It introduced several bug fixes, addressing a weather widget bug and fixing issue that could cause NFC not to work in iPhone models charged with a BMW wireless charger.
Apple is also testing iOS 17.2, an update that is expected to come out in December.