Hi there, this is what AI just told me because I thought our MDM is blocking the process and I specifically asked AI about it again. Let your MDM know about this: **PSA: iOS 18.5 Simulator Issues with Defender/Cisco AnyConnect - Architecture Change** If you're experiencing issues with iOS 18.5 simulators failing to launch while iOS 18.2 and earlier simulators work fine, this may be due to a fundamental architecture change Apple introduced: **What Changed:** Apple changed the simulator architecture in iOS 18.5 (and macOS 15.x): **iOS 18.2 and earlier:** - Simulator ran as a single process - launchd_sim was a simple subprocess - Minimal network communication - ✅ Works with security software like Defender/AnyConnect **iOS 18.5+ (and iPhone 17.x simulators):** - New "Virtualization Framework" integration - Simulator now uses multiple isolated processes - launchd_sim binds to virtual network interfaces (vmnet) - Attempts to bind to 127.0.0.1:XXXX for localhost communication between processes - Requires new system extensions **The Problem:** When the iOS 18.5 simulator starts: 1. It attempts to build a virtual network (vmnet) 2. launchd_sim tries to bind to 127.0.0.1:XXXX 3. 🚫 Microsoft Defender Web Content Filter blocks this 4. 🚫 Cisco AnyConnect VPN also blocks this 5. → Simulator fails to launch **Workaround:** You may need to temporarily disable or configure exceptions in: - Microsoft Defender Web Content Filter - Cisco AnyConnect VPN - Any other network security software This appears to be a side effect of Apple's new virtualization-based simulator architecture requiring more localhost network access. I will keep you updated if that was the case. If anyone else can confirm going this direction was successful - please let us know.

Hi all, we do have the same problem. Me and several other colleagues. We just found out the same that iOS Simulator version 18.2 is the latest working for us. We have also tried to clean everything and start the installation from scratch. It did not help. I throw my stack trace here as well in the hope it might be seen and it might help some developer at Apple. Unable to boot the Simulator. Domain: NSPOSIXErrorDomain Code: 4 Failure Reason: Interrupted system call User Info: { DVTErrorCreationDateKey = "2026-01-14 08:42:36 +0000"; IDERunOperationFailingWorker = "_IDEInstalliPhoneSimulatorWorker"; Session = "com.apple.CoreSimulator.SimDevice.79733B3C-A5BA-41E8-A88A-6DA408E517D6"; } -- 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 -- Event Metadata: com.apple.dt.IDERunOperationWorkerFinished : { "device_identifier" = "XXX"; "device_model" = "iPhone17,5"; "device_osBuild" = "26.0 (23A339)"; "device_osBuild_monotonic" = 2300033900; "device_os_variant" = 1; "device_platform" = "com.apple.platform.iphonesimulator"; "device_platform_family" = 2; "device_reality" = 2; "device_thinningType" = "iPhone17,5"; "device_transport" = 4; "launchSession_schemeCommand" = Run; "launchSession_schemeCommand_enum" = 1; "launchSession_targetArch" = arm64; "launchSession_targetArch_enum" = 6; "operation_duration_ms" = 975; "operation_errorCode" = 4; "operation_errorDomain" = NSPOSIXErrorDomain; "operation_errorWorker" = "_IDEInstalliPhoneSimulatorWorker"; "operation_error_reportable" = 1; "operation_name" = IDERunOperationWorkerGroup; "param_consoleMode" = 1; "param_debugger_attachToExtensions" = 0; "param_debugger_attachToXPC" = 1; "param_debugger_type" = 3; "param_destination_isProxy" = 0; "param_destination_platform" = "com.apple.platform.iphonesimulator"; "param_diag_MTE_enable" = 0; "param_diag_MainThreadChecker_stopOnIssue" = 0; "param_diag_MallocStackLogging_enableDuringAttach" = 0; "param_diag_MallocStackLogging_enableForXPC" = 1; "param_diag_allowLocationSimulation" = 1; "param_diag_checker_mtc_enable" = 1; "param_diag_checker_tpc_enable" = 1; "param_diag_gpu_frameCapture_enable" = 0; "param_diag_gpu_shaderValidation_enable" = 0; "param_diag_gpu_validation_enable" = 0; "param_diag_guardMalloc_enable" = 0; "param_diag_memoryGraphOnResourceException" = 0; "param_diag_queueDebugging_enable" = 1; "param_diag_runtimeProfile_generate" = 0; "param_diag_sanitizer_asan_enable" = 0; "param_diag_sanitizer_tsan_enable" = 0; "param_diag_sanitizer_tsan_stopOnIssue" = 0; "param_diag_sanitizer_ubsan_enable" = 0; "param_diag_sanitizer_ubsan_stopOnIssue" = 0; "param_diag_showNonLocalizedStrings" = 0; "param_diag_viewDebugging_enabled" = 1; "param_diag_viewDebugging_insertDylibOnLaunch" = 1; "param_install_style" = 2; "param_launcher_UID" = 2; "param_launcher_allowDeviceSensorReplayData" = 0; "param_launcher_kind" = 0; "param_launcher_style" = 0; "param_launcher_substyle" = 0; "param_lldbVersion_component_idx_1" = 0; "param_lldbVersion_monotonic" = 170302340003; "param_runnable_appExtensionHostRunMode" = 0; "param_runnable_productType" = "com.apple.product-type.application"; "param_testing_launchedForTesting" = 0; "param_testing_suppressSimulatorApp" = 0; "param_testing_usingCLI" = 0; "sdk_canonicalName" = "iphonesimulator26.1"; "sdk_osVersion" = "26.1"; "sdk_platformID" = 7; "sdk_variant" = iphonesimulator; "sdk_version_monotonic" = 2301007700; } -- System Information macOS Version 15.7.3 (Build 24G419) Xcode 26.1.1 (24455) (Build 17B100) Timestamp: 2026-01-14T09:42:36+01:00