Environment: macOS 26.5.1 (Build 25F80) Xcode 26.6 (Build 17F113) iOS 26.5 Simulator Runtime (Build 23F77) Device: Apple Silicon (arm64) Summary: The iOS 26.5 simulator fails to boot with NSPOSIXErrorDomain Code 4 (Interrupted system call). The underlying error indicates launchd_sim cannot bind to its session, suggesting the CoreSimulator session management is broken in this macOS + Xcode + runtime combination. Steps to Reproduce: Install macOS 26.5.1 and Xcode 26.6 Open Simulator.app or run xcrun simctl boot Attempt to boot any iOS 26.5 simulator device Expected Result: Simulator boots successfully and reaches the Booted state. Actual Result: Unable to boot the Simulator. Domain: NSPOSIXErrorDomain Code: 4 Failure Reason: Interrupted system call Failed to start launchd_sim: could not bind to session, launchd_sim may have crashed or quit responding Domain: com.apple.SimLaunchHostService.RequestError Code: 4 Workaround: Installing an older stable iOS simulator runtime (iOS 17.x or 18.x) and targeting that instead allows simulators to boot normally. Additional Notes: Issue persists after full Mac restart xcrun simctl erase all and xcrun simctl delete all do not resolve it The iOS 26.5 Simulator volume mounts correctly at /Library/Developer/CoreSimulator/Volumes/iOS_23F77 launchd_sim binary is present and properly code-signed