Yeah, I found a solution. On Apple Watch Ultra, WKBackgroundModes = underwater-depth and the shallow-depth entitlement weren’t sufficient. Add a StartDiveIntent directly to the watch app target: import AppIntents struct StartAppDiveIntent: StartDiveIntent { static let title: LocalizedStringResource = "Start App static var openAppWhenRun: Bool { true } func perform() async throws -> some IntentResult { .result() } } Then call WKExtendedRuntimeSession.requestAutoLaunchAuthorizationStatus only after the app is fully foreground-active. Without the intent, Ultra returns error 10; calling too early returns error 9. No full-depth entitlement or WKSupportsAutomaticDepthLaunch key is needed. The Simulator cannot validate this - test on physical hardware.