This is a somewhat common but longstanding Mac crash that has affected users since at least 4.13.
Recently in 4.17.1, the crashes are all occurring in various ARKit projects
User Descriptions
Callstack from Log
Error: appError called: Assertion failed: Assertion failed: [File:/Users/build/Build/++UE4+Release-4.17+Compile/Sync/Engine/Source/Editor/UnrealEd/Private/EditorServer.cpp] [Line: 1928] /Game/Maps/*** still around trying to load ../../../../../../***/Downloads/***/Content/Maps/***.umap (Object is not currently rooted) === Critical error: === SIGSEGV: invalid attempt to access memory at address 0x3 FGenericPlatformMisc::RaiseException(unsigned int) Address = 0x185fadb (filename not found) [in UE4Editor-Core.dylib] FOutputDeviceMacError::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&) Address = 0x1a7708f (filename not found) [in UE4Editor-Core.dylib] FOutputDevice::Logf(wchar_t const*, ...) Address = 0x1b5d8fd (filename not found) [in UE4Editor-Core.dylib] FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...) Address = 0x1ab07ce (filename not found) [in UE4Editor-Core.dylib] UEditorEngine::CheckForWorldGCLeaks(UWorld*, UPackage*) Address = 0x923fc5a (filename not found) [in UE4Editor-UnrealEd.dylib] UEditorEngine::EditorDestroyWorld(FWorldContext&, FText const&, UWorld*) Address = 0x924127f (filename not found) [in UE4Editor-UnrealEd.dylib] UEditorEngine::Map_Load(wchar_t const*, FOutputDevice&) Address = 0x9245dfe (filename not found) [in UE4Editor-UnrealEd.dylib] UEditorEngine::HandleMapCommand(wchar_t const*, FOutputDevice&, UWorld*) Address = 0x9269b25 (filename not found) [in UE4Editor-UnrealEd.dylib] UEditorEngine::Exec(UWorld*, wchar_t const*, FOutputDevice&) Address = 0x9266611 (filename not found) [in UE4Editor-UnrealEd.dylib] UUnrealEdEngine::Exec(UWorld*, wchar_t const*, FOutputDevice&) Address = 0x9eae639 (filename not found) [in UE4Editor-UnrealEd.dylib] FEditorFileUtils::LoadMap(FString const&, bool, bool) Address = 0x96a33cb (filename not found) [in UE4Editor-UnrealEd.dylib] FAssetTypeActions_World::OpenAssetEditor(TArray<UObject*, FDefaultAllocator> const&, TSharedPtr<IToolkitHost, (ESPMode)0>) Address = 0x1acf44d7 (filename not found) [in UE4Editor-AssetTools.dylib] FAssetEditorManager::OpenEditorForAsset(UObject*, EToolkitMode::Type, TSharedPtr<IToolkitHost, (ESPMode)0>) Address = 0x9e3c5cd (filename not found) [in UE4Editor-UnrealEd.dylib] FAssetTypeActions_Base::AssetsActivated(TArray<UObject*, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type) Address = 0x1acc6dac (filename not found) [in UE4Editor-AssetTools.dylib] SContentBrowser::OnAssetsActivated(TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type) Address = 0x197418e6 (filename not found) [in UE4Editor-ContentBrowser.dylib] TBaseSPMethodDelegateInstance<false, SContentBrowser, (ESPMode)0, TTypeWrapper<void> (TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type)>::Execute(TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type) const Address = 0x198039a0 (filename not found) [in UE4Editor-ContentBrowser.dylib] TBaseSPMethodDelegateInstance<false, SContentBrowser, (ESPMode)0, void (TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type)>::ExecuteIfSafe(TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type) const Address = 0x19803a4b (filename not found) [in UE4Editor-ContentBrowser.dylib] SAssetView::OnListMouseButtonDoubleClick(TSharedPtr<FAssetViewItem, (ESPMode)0>) Address = 0x196d1f42 (filename not found) [in UE4Editor-ContentBrowser.dylib] _ZN21TMemberFunctionCallerI10SAssetViewMS0_Fv10TSharedPtrI14FAssetViewItemL7ESPMode0EEEEclIJRS4_EEEDTclpmdtdefpT3ObjdtdefpT9MemFunPtrspcl7ForwardIT_Efp_EEEDpOSA_() Address = 0x197a8ec3 (filename not found) [in UE4Editor-ContentBrowser.dylib] TBaseSPMethodDelegateInstance<false, SAssetView, (ESPMode)0, TTypeWrapper<void> (TSharedPtr<FAssetViewItem, (ESPMode)0>)>::Execute(TSharedPtr<FAssetViewItem, (ESPMode)0>) const Address = 0x197a8cea (filename not found) [in UE4Editor-ContentBrowser.dylib] TBaseSPMethodDelegateInstance<false, SAssetView, (ESPMode)0, void (TSharedPtr<FAssetViewItem, (ESPMode)0>)>::ExecuteIfSafe(TSharedPtr<FAssetViewItem, (ESPMode)0>) const Address = 0x197a8da9 (filename not found) [in UE4Editor-ContentBrowser.dylib] TBaseDelegate<void, TSharedPtr<FAssetViewItem, (ESPMode)0> >::ExecuteIfBound(TSharedPtr<FAssetViewItem, (ESPMode)0>) const Address = 0x196524a3 (filename not found) [in UE4Editor-ContentBrowser.dylib] SListView<TSharedPtr<FAssetViewItem, (ESPMode)0> >::Private_OnItemDoubleClicked(TSharedPtr<FAssetViewItem, (ESPMode)0>) Address = 0x195b1552 (filename not found) [in UE4Editor-ContentBrowser.dylib] STableRow<TSharedPtr<FAssetViewItem, (ESPMode)0> >::OnMouseButtonDoubleClick(FGeometry const&, FPointerEvent const&) Address = 0x19655147 (filename not found) [in UE4Editor-ContentBrowser.dylib] non-virtual thunk to STableRow<TSharedPtr<FAssetViewItem, (ESPMode)0> >::OnMouseButtonDoubleClick(FGeometry const&, FPointerEvent const&) Address = 0x1965a852 (filename not found) [in UE4Editor-ContentBrowser.dylib] FSlateApplication::RoutePointerDoubleClickEvent(FWidgetPath&, FPointerEvent&) Address = 0x7d99d27 (filename not found) [in UE4Editor-Slate.dylib] FSlateApplication::ProcessMouseButtonDoubleClickEvent(TSharedPtr<FGenericWindow, (ESPMode)0> const&, FPointerEvent&) Address = 0x7d99295 (filename not found) [in UE4Editor-Slate.dylib] FSlateApplication::OnMouseDoubleClick(TSharedPtr<FGenericWindow, (ESPMode)0> const&, EMouseButtons::Type, FVector2D) Address = 0x7d988be (filename not found) [in UE4Editor-Slate.dylib] FMacApplication::ProcessMouseDownEvent(FDeferredMacEvent const&, TSharedPtr<FMacWindow, (ESPMode)0>) Address = 0x1a47558 (filename not found) [in UE4Editor-Core.dylib] FMacApplication::ProcessEvent(FDeferredMacEvent const&) Address = 0x1a3d9cb (filename not found) [in UE4Editor-Core.dylib] FMacApplication::ProcessDeferredEvents(float) Address = 0x1a3b7bf (filename not found) [in UE4Editor-Core.dylib] FSlateApplication::TickPlatform(float) Address = 0x7d5c66b (filename not found) [in UE4Editor-Slate.dylib] FSlateApplication::Tick(ESlateTickType) Address = 0x7d5baa4 (filename not found) [in UE4Editor-Slate.dylib] FEngineLoop::Tick() Address = 0x4e6011 (filename not found) [in UE4Editor] GuardedMain(wchar_t const*) Address = 0x4ecc22 (filename not found) [in UE4Editor] -[UE4AppDelegate runGameThread:] Address = 0x4fa5d0 (filename not found) [in UE4Editor] -[FCocoaGameThread main] Address = 0x1a32cc6 (filename not found) [in UE4Editor-Core.dylib] __NSThread__start__() Address = 0x37ca06d8 (filename not found) [in Foundation] _pthread_body() Address = 0x5d3d36c1 (filename not found) [in libsystem_pthread.dylib] _pthread_body() Address = 0x5d3d356d (filename not found) [in libsystem_pthread.dylib] thread_start() Address = 0x5d3d2c5d (filename not found) [in libsystem_pthread.dylib]
repro steps currently unknown
SEGV_MAPERR at 0x3 UE4Editor-UnrealEd.dylib!UEditorEngine::CheckForWorldGCLeaks() UE4Editor-UnrealEd.dylib!UEditorEngine::EditorDestroyWorld() UE4Editor-UnrealEd.dylib!UEditorEngine::Map_Load() UE4Editor-UnrealEd.dylib!UEditorEngine::HandleMapCommand() UE4Editor-UnrealEd.dylib!UEditorEngine::Exec() UE4Editor-UnrealEd.dylib!UUnrealEdEngine::Exec() UE4Editor-UnrealEd.dylib!FEditorFileUtils::LoadMap() UE4Editor-AssetTools.dylib!FAssetTypeActions_World::OpenAssetEditor(TArray<UObject*, FDefaultAllocator> const&, TSharedPtr<IToolkitHost,() UE4Editor-UnrealEd.dylib!FAssetEditorManager::OpenEditorForAsset(UObject*, EToolkitMode::Type, TSharedPtr<IToolkitHost,() UE4Editor-AssetTools.dylib!FAssetTypeActions_Base::AssetsActivated() UE4Editor-ContentBrowser.dylib!SContentBrowser::OnAssetsActivated() UE4Editor-ContentBrowser.dylib!TBaseSPMethodDelegateInstance<false, SContentBrowser, (ESPMode)0, TTypeWrapper<void> (TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type)>::Execute() UE4Editor-ContentBrowser.dylib!TBaseSPMethodDelegateInstance<false, SContentBrowser, (ESPMode)0, void (TArray<FAssetData, FDefaultAllocator> const&, EAssetTypeActivationMethod::Type)>::ExecuteIfSafe() UE4Editor-ContentBrowser.dylib!SAssetView::OnListMouseButtonDoubleClick(TSharedPtr<FAssetViewItem,() UE4Editor-ContentBrowser.dylib!<Unknown> UE4Editor-ContentBrowser.dylib!TBaseSPMethodDelegateInstance<false, SAssetView, (ESPMode)0, TTypeWrapper<void> (TSharedPtr<FAssetViewItem, (ESPMode)0>)>::Execute(TSharedPtr<FAssetViewItem,() UE4Editor-ContentBrowser.dylib!TBaseSPMethodDelegateInstance<false, SAssetView, (ESPMode)0, void (TSharedPtr<FAssetViewItem, (ESPMode)0>)>::ExecuteIfSafe(TSharedPtr<FAssetViewItem,() UE4Editor-ContentBrowser.dylib!TBaseDelegate<void, TSharedPtr<FAssetViewItem, (ESPMode)0> >::ExecuteIfBound(TSharedPtr<FAssetViewItem,() UE4Editor-ContentBrowser.dylib!SListView<TSharedPtr<FAssetViewItem, (ESPMode)0> >::Private_OnItemDoubleClicked(TSharedPtr<FAssetViewItem,() UE4Editor-ContentBrowser.dylib!STableRow<TSharedPtr<FAssetViewItem, (ESPMode)0> >::OnMouseButtonDoubleClick() UE4Editor-ContentBrowser.dylib!non-virtual thunk to STableRow<TSharedPtr<FAssetViewItem, (ESPMode)0> >::OnMouseButtonDoubleClick() UE4Editor-Slate.dylib!FSlateApplication::RoutePointerDoubleClickEvent() UE4Editor-Slate.dylib!FSlateApplication::ProcessMouseButtonDoubleClickEvent(TSharedPtr<FGenericWindow,() UE4Editor-Slate.dylib!FSlateApplication::OnMouseDoubleClick(TSharedPtr<FGenericWindow,() UE4Editor-Core.dylib!FMacApplication::ProcessMouseDownEvent(FDeferredMacEvent const&, TSharedPtr<FMacWindow,() UE4Editor-Core.dylib!FMacApplication::ProcessEvent() UE4Editor-Core.dylib!FMacApplication::ProcessDeferredEvents() UE4Editor-Slate.dylib!FSlateApplication::TickPlatform() UE4Editor-Slate.dylib!FSlateApplication::Tick() UE4Editor!FEngineLoop::Tick() UE4Editor!GuardedMain() UE4Editor!<Unknown> UE4Editor-Core.dylib!<Unknown> Foundation!Unknown() libsystem_pthread.dylib!<Unknown> libsystem_pthread.dylib!<Unknown> libsystem_pthread.dylib!<Unknown>
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-49497 in the post.