Apple Watch watchOS 27 Update: The iPhone Step Apple Requires First, and the 50 Percent Battery Rule

watchOS 27 arrives free on Monday, September 14, 2026, and Apple’s own support page sets two conditions before it will install: the paired iPhone must already be running iOS 27, and the Apple Watch itself must be at least 50 percent charged. Miss either one and Software Update will not offer the download. watchOS 27 will not install until the...