Apple stops signing iOS 26.5 and 26.5.1, blocking downgrades after critical security fix

Apple has stopped signing iOS 26.5 and iOS 26.5.1, meaning users can no longer downgrade to those versions after updating to a newer release. The move follows the release of a critical security patch for iPhone last week. Blocking downgrades after significant security fixes is Apple's standard practice to ensure users stay on protected software.