iOS Simulator fails to boot (18.6 / 26.1 / 26.2) – launchd_sim could not bind to session

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

I have the same issue. launchd_sim could not bind to session on iOS 18.6 / 26.1 / 26.2 but when I downloaded 18.2 it worked fine.

I tried clearing ~/Library/Developer/Xcode/DerivedData and /Library/Caches/com.apple.dt.Xcode but no success.

I tried removing project build caches from System Settings -> Storage -> Storage Settings -> Developer, but no success.

I deleted iOS Simulator 26.1 platform from Xcode > Settings > Components and then re-adding it but still no success.

Having the same issue, Macos Tahoe 26.2, i tried everything i found on net: deleting caches, all xcode files, reinstalling it, rebooting my computer, deleting all simalator devices, deleting IOS from Xcode => setting components, downloading it again. I tried installing older IOS, no help, when starting emulator i have this error: "Unable to boot the Simulator"

And this error, when i'm trying to do this from terminal

== Devices ==
-- iOS 26.2 --
    iPhone 17 Pro (1FC8FFC9-A04D-434B-85F0-F5AE2DB4CDAC) (Shutdown) 
    iPhone 17 Pro Max (71761C54-D406-496E-A552-CD72FACD10DA) (Shutdown) 
    iPhone Air (64607ACA-F580-4A6A-A816-1AD1E8BEBC32) (Shutdown) 
    iPhone 17 (7ECEC4C0-0DC9-4B5A-A9A0-05E4B1038C68) (Shutdown) 
    iPhone 16e (A175B467-438D-41A7-B537-D7E23B4FFF21) (Shutdown) 
    iPad Pro 13-inch (M5) (FA74F9C7-93C9-40D6-86F5-74E46FCCF7EC) (Shutdown) 
    iPad Pro 11-inch (M5) (73A17C77-DBFA-4748-880D-15FBBE43E57E) (Shutdown) 
    iPad mini (A17 Pro) (09BF89D2-640C-4083-937A-4859633BB69E) (Shutdown) 
    iPad (A16) (5FF5869B-042F-4886-A5E3-AD333550F9EB) (Shutdown) 
    iPad Air 13-inch (M3) (3474F7D9-68B1-46AE-94F1-91DF48E38464) (Shutdown) 
    iPad Air 11-inch (M3) (8EDB1407-74CB-4420-86A2-C0AD084D8A73) (Shutdown) 
[~] xcrun simctl boot 1FC8FFC9-A04D-434B-85F0-F5AE2DB4CDAC                     
An error was encountered processing the command (domain=NSPOSIXErrorDomain, code=4):
Unable to boot the Simulator.
Interrupted system call
Underlying error (domain=com.apple.SimLaunchHostService.RequestError, code=4):
	Failed to start launchd_sim: could not bind to session, launchd_sim may have crashed or quit responding

Please, help

I’m facing an issue where iOS Simulator versions 18.6 and above (including iOS 26.0.1) fail to boot, while older simulators like iOS 18.0 / 18.2 work fine on the same machine. Environment macOS 26.2 (Build 25C56) Xcode 26.0 (Build 17A324) iOS Simulator runtimes: iOS 18.0 – works iOS 18.6 – fails to boot iOS 26.0.1 – fails to boot Error observed Unable to boot the Simulator NSPOSIXErrorDomain Code: 4 (Interrupted system call)

Failed to start launchd_sim: could not bind to session, launchd_sim may have crashed or quit responding This happens even when launching the Simulator app directly (without running any app). Steps already tried (no success) Shut down and erased all simulators: xcrun simctl shutdown all xcrun simctl erase all Deleted CoreSimulator data: rm -rf ~/Library/Developer/CoreSimulator killall -9 com.apple.CoreSimulator.CoreSimulatorService Rebooted macOS multiple times Reinstalled simulator runtimes via Xcode → Settings → Platforms Attempted runtime deletion using: xcrun simctl runtime delete (No matching runtime found / runtimes reappear) Verified that legacy runtime path /Library/Developer/CoreSimulator/Profiles/Runtimes no longer exists on macOS 26 (runtimes appear to be managed by AssetRuntime) Observation iOS 18.0 simulator consistently boots iOS 18.6+ and iOS 26.0.1 always fail Issue appears unrelated to project or app code Conclusion / Question This looks like a CoreSimulator / AssetRuntime regression affecting newer simulator runtimes on macOS 26 + Xcode 26. Has anyone else seen this issue? Is there a known workaround, or is this fixed in an upcoming Xcode/macOS update?

Hi, I have the same issue since 6 months. I tried the same things as above and reported it several times to Apple. But no reaction from Apple so far.

Does anyone have a solution?