Hello everyone,
I am currently developing an iMessage Sticker Pack in Xcode 16.4 (Build 16F6) on macOS 15.6.1.
The project builds without errors, but when running in the iOS 18.6 Simulator (iPhone 15 Pro, iPhone 16, etc.), the Sticker Pack does not show up inside Messages. Instead, the Simulator displays a white screen or the sticker drawer simply does not include my extension.
In the logs I consistently see this error:
FrontBoard[app] error: Application "de.eazyapp.smileystickerpack.StickerPackExtension" is unknown to FrontBoard
Simulator device failed to launch de.eazyapp.smileystickerpack. Domain: FBSOpenApplicationServiceErrorDomain Code: 1 Failure Reason: The request was denied by service delegate (SBMainWorkspace) for reason: NotFound ("Application "de.eazyapp.smileystickerpack" is unknown to FrontBoard"). User Info: { BSErrorCodeDescription = RequestDenied; DVTErrorCreationDateKey = "2025-08-21 10:11:22 +0000"; FBSOpenApplicationRequestID = 0x6e63; IDERunOperationFailingWorker = IDELaunchiPhoneSimulatorLauncher; SimCallingSelector = "launchApplicationWithID:options:pid:error:"; }
The request to open "de.eazyapp.smileystickerpack" failed. Domain: FBSOpenApplicationServiceErrorDomain Code: 1 Failure Reason: The request was denied by service delegate (SBMainWorkspace) for reason: NotFound ("Application "de.eazyapp.smileystickerpack" is unknown to FrontBoard"). User Info: { BSErrorCodeDescription = RequestDenied; FBSOpenApplicationRequestID = 0x6e63; }
The operation couldn’t be completed. Application "de.eazyapp.smileystickerpack" is unknown to FrontBoard. Domain: FBSOpenApplicationErrorDomain Code: 4 Failure Reason: Application "de.eazyapp.smileystickerpack" is unknown to FrontBoard. User Info: { BSErrorCodeDescription = NotFound; }
Event Metadata: com.apple.dt.IDERunOperationWorkerFinished : { "device_identifier" = "A3986FB9-55ED-42CC-9336-F695C4CB9451"; "device_model" = "iPhone17,1"; "device_osBuild" = "18.6 (22G86)"; "device_platform" = "com.apple.platform.iphonesimulator"; "device_thinningType" = "iPhone17,1"; "dvt_coredevice_version" = "443.24"; "dvt_coresimulator_version" = "1010.15"; "dvt_mobiledevice_version" = "1784.140.4"; "launchSession_schemeCommand" = Run; "launchSession_state" = 1; "launchSession_targetArch" = arm64; "operation_duration_ms" = 23478; "operation_errorCode" = 1; "operation_errorDomain" = FBSOpenApplicationServiceErrorDomain; "operation_errorWorker" = IDELaunchiPhoneSimulatorLauncher; "operation_name" = IDERunOperationWorkerGroup; "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_113575882_enable" = 0; "param_diag_MainThreadChecker_stopOnIssue" = 0; "param_diag_MallocStackLogging_enableDuringAttach" = 0; "param_diag_MallocStackLogging_enableForXPC" = 1; "param_diag_allowLocationSimulation" = 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_mtc_enable" = 1; "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_runnable_appExtensionHostRunMode" = 0; "param_runnable_productType" = "com.apple.product-type.application.messages"; "param_structuredConsoleMode" = 1; "param_testing_launchedForTesting" = 0; "param_testing_suppressSimulatorApp" = 0; "param_testing_usingCLI" = 0; "sdk_canonicalName" = "iphonesimulator18.5"; "sdk_osVersion" = "18.5"; "sdk_variant" = iphonesimulator; }
System Information
macOS Version 15.6.1 (Build 24G90) Xcode 16.4 (23792) (Build 16F6) Timestamp: 2025-08-21T12:11:22+02:00
Steps I already tried:
Verified Bundle Identifiers (App + Extension)
Confirmed Stickers.xcstickers is only in the Extension target, not the App target
Checked that the Extension is properly listed under Embed Foundation Extensions
Performed Clean Build Folder, Simulator reset, and reinstall
Tried on a fresh Mac with clean Xcode install
Reproduced consistently across multiple iOS 18 Simulators
Steps to reproduce Create new iMessage Sticker Pack App in Xcode Add PNG/APNG stickers into Stickers.xcstickers
Run on Simulator (iOS 18.6) Open Messages → App Drawer Sticker Pack is missing, extension does not load Environment
Xcode 16.4 (16F6) macOS 15.6.1 (24G90) iOS Simulator 18.6 Project type: iMessage Sticker Pack Question Has anyone else experienced this issue with iMessage Sticker Packs on iOS 18 Simulators?
Any guidance would be appreciated Thank you, Hakan
