Apple on Monday stopped signing code for iOS 13.5 following the release of iOS 13.5.1 last week, effectively blocking users from downgrading to the previous operating system.
Today's stoppage means users can no longer download the out-of-date operating system from Apple's servers. Apple regularly ceases signing of older code to prevent installation of past iOS versions following the release of a new variant, a practice that keeps users safe from new threats and ensures devices are running the latest feature-rich software.
Prior to iOS 13.5.1, Apple pushed out the more substantial iOS 13.5 update, and corresponding iPadOS, macOS, tvOS and watchOS releases, with new features related to COVID-19. In addition to a public launch of the Apple-Google Exposure Notification system, the operating systems offer a faster Face ID unlocking process for users wearing protective masks.