Overview

• Apple ended signing for iOS 18.6 this week, making downgrades from iOS 18.6.1 or iOS 18.6.2 to that build no longer possible.
• iOS 18.6.1 and iOS 18.6.2 remain available for restores, with 18.6.2 arriving Wednesday as a security-focused update.
• The 18.6.1 release restored blood oxygen monitoring in the United States for Apple Watch Series 9, Series 10, and Ultra 2 when paired with watchOS 11.6.1.
• Apple routinely closes signing windows shortly after new releases to keep devices on versions with the latest protections and to curb exploits targeted by jailbreaks.
• Most users cannot install unsigned firmware, though organizations may still use the DelayOTA enterprise method for a limited window to move up to iOS 18.6 from older versions.