This is an infrequent Mac crash in the 4.18 release.
The callstack is a match to [Link Removed] (loading Zen editor on Mac), but that was confirmed fixed for 4.18.0 while this continues for users.
User Descriptions
Callstack from Log
[2017.11.16-11.10.48:274][ 0]LogMac: Error: appError called: Assertion failed: [File:/Users/build/Build/++UE4+Release-4.18+Compile/Sync/Engine/Source/Runtime/Engine/Private/ShaderCompiler/ShaderCompiler.cpp] [Line: 1827] Failed to compile default material /Engine/EngineMaterials/WorldGridMaterial.WorldGridMaterial! [2017.11.16-11.10.48:391][ 0]LogMac: === Critical error: === SIGSEGV: invalid attempt to access memory at address 0x3 [2017.11.16-11.10.48:391][ 0]LogMac: 0x046ea99b UE4Editor-Core.dylib!FGenericPlatformMisc::RaiseException(unsigned int) [UnknownFile]) 0x0a1f0c09 UE4Editor-ApplicationCore.dylib!FMacErrorOutputDevice::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&) [UnknownFile]) 0x04998c9d UE4Editor-Core.dylib!FOutputDevice::Logf(wchar_t const*, ...) [UnknownFile]) 0x0490eefb UE4Editor-Core.dylib!FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...) [UnknownFile]) 0x06f48562 UE4Editor-Engine.dylib!FShaderCompilingManager::ProcessCompiledShaderMaps(TMap<int, FShaderMapFinalizeResults, FDefaultSetAllocator, TDefaultMapHashableKeyFuncs<int, FShaderMapFinalizeResults, false> >&, float) [UnknownFile]) 0x06f4fdb6 UE4Editor-Engine.dylib!FShaderCompilingManager::FinishCompilation(wchar_t const*, TArray<int, FDefaultAllocator> const&) [UnknownFile]) 0x069b236c UE4Editor-Engine.dylib!FMaterialShaderMap::Compile(FMaterial*, FMaterialShaderMapId const&, TRefCountPtr<FShaderCompilerEnvironment>, FMaterialCompilationOutput const&, EShaderPlatform, bool, bool) [UnknownFile]) 0x069cff1b UE4Editor-Engine.dylib!FMaterial::BeginCompileShaderMap(FMaterialShaderMapId const&, EShaderPlatform, TRefCountPtr<FMaterialShaderMap>&, bool) [UnknownFile]) 0x069cf377 UE4Editor-Engine.dylib!FMaterial::CacheShaders(FMaterialShaderMapId const&, EShaderPlatform, bool) [UnknownFile]) 0x069cef76 UE4Editor-Engine.dylib!FMaterial::CacheShaders(EShaderPlatform, bool) [UnknownFile]) 0x068939b6 UE4Editor-Engine.dylib!UMaterial::CacheShadersForResources(EShaderPlatform, TArray<FMaterialResource*, FDefaultAllocator> const&, bool) [UnknownFile]) 0x0688c2b3 UE4Editor-Engine.dylib!UMaterial::CacheResourceShadersForRendering(bool) [UnknownFile]) 0x06897f08 UE4Editor-Engine.dylib!UMaterial::PostLoad() [UnknownFile]) 0x0552e904 UE4Editor-CoreUObject.dylib!UObject::ConditionalPostLoad() [UnknownFile]) 0x0688343f UE4Editor-Engine.dylib!UMaterialInterface::PostLoadDefaultMaterials() [UnknownFile]) 0x06994084 UE4Editor-Engine.dylib!UMaterialInterface::PostLoad() [UnknownFile]) 0x06896d7a UE4Editor-Engine.dylib!UMaterial::PostLoad() [UnknownFile]) 0x0552e904 UE4Editor-CoreUObject.dylib!UObject::ConditionalPostLoad() [UnknownFile]) 0x056eed18 UE4Editor-CoreUObject.dylib!EndLoad() [UnknownFile]) 0x056ed43a UE4Editor-CoreUObject.dylib!LoadPackageInternal(UPackage*, wchar_t const*, unsigned int, FLinkerLoad*) [UnknownFile]) 0x056ea3fb UE4Editor-CoreUObject.dylib!LoadPackage(UPackage*, wchar_t const*, unsigned int) [UnknownFile]) 0x056e6827 UE4Editor-CoreUObject.dylib!ResolveName(UObject*&, FString&, bool, bool, unsigned int) [UnknownFile]) 0x056eabd8 UE4Editor-CoreUObject.dylib!StaticLoadObjectInternal(UClass*, UObject*, wchar_t const*, wchar_t const*, unsigned int, UPackageMap*, bool) [UnknownFile]) 0x056e54f8 UE4Editor-CoreUObject.dylib!StaticLoadObject(UClass*, UObject*, wchar_t const*, wchar_t const*, unsigned int, UPackageMap*, bool) [UnknownFile]) 0x06123b2d UE4Editor-Engine.dylib!UStaticMesh* ConstructorHelpersInternal::FindOrLoadObject<UStaticMesh>(FString&) [UnknownFile]) 0x0612342d UE4Editor-Engine.dylib!ConstructorHelpers::FObjectFinder<UStaticMesh>::FObjectFinder(wchar_t const*) [UnknownFile]) 0x060cbe86 UE4Editor-Engine.dylib!UCameraComponent::UCameraComponent(FObjectInitializer const&) [UnknownFile]) 0x05417684 UE4Editor-CoreUObject.dylib!UClass::CreateDefaultObject() [UnknownFile]) 0x05708f71 UE4Editor-CoreUObject.dylib!FObjectInitializer::CreateDefaultSubobject(UObject*, FName, UClass*, UClass*, bool, bool, bool) const [UnknownFile]) 0x0552307d UE4Editor-CoreUObject.dylib!UObject::CreateDefaultSubobject(FName, UClass*, UClass*, bool, bool, bool) [UnknownFile]) 0x060c6d3b UE4Editor-Engine.dylib!ACameraActor::ACameraActor(FObjectInitializer const&) [UnknownFile]) 0x05417684 UE4Editor-CoreUObject.dylib!UClass::CreateDefaultObject() [UnknownFile]) 0x056d42ac UE4Editor-CoreUObject.dylib!ProcessNewlyLoadedUObjects() [UnknownFile]) 0x041f5a22 UE4Editor!FEngineLoop::PreInit(wchar_t const*) [UnknownFile]) 0x0420a491 UE4Editor!GuardedMain(wchar_t const*) [UnknownFile]) 0x04217e40 UE4Editor!-[UE4AppDelegate runGameThread:] [UnknownFile]) 0x04894d17 UE4Editor-Core.dylib!-[FCocoaGameThread main] [UnknownFile]) 0x53a506d8 Foundation!__NSThread__start__() [UnknownFile]) 0x791876c1 libsystem_pthread.dylib!_pthread_body() [UnknownFile]) 0x7918756d libsystem_pthread.dylib!_pthread_body() [UnknownFile]) 0x79186c5d libsystem_pthread.dylib!thread_start() [UnknownFile])
repro steps currently unknown
UE4Editor-Engine.dylib!FShaderCompilingManager::ProcessCompiledShaderMaps() UE4Editor-Engine.dylib!FShaderCompilingManager::FinishCompilation() UE4Editor-Engine.dylib!FMaterialShaderMap::Compile() UE4Editor-Engine.dylib!FMaterial::BeginCompileShaderMap() UE4Editor-Engine.dylib!FMaterial::CacheShaders() UE4Editor-Engine.dylib!FMaterial::CacheShaders() UE4Editor-Engine.dylib!UMaterial::CacheShadersForResources() UE4Editor-Engine.dylib!UMaterial::CacheResourceShadersForRendering() UE4Editor-Engine.dylib!UMaterial::PostLoad() UE4Editor-CoreUObject.dylib!UObject::ConditionalPostLoad() UE4Editor-Engine.dylib!UMaterialInterface::PostLoadDefaultMaterials() UE4Editor-Engine.dylib!UMaterialInterface::PostLoad() UE4Editor-Engine.dylib!UMaterial::PostLoad() UE4Editor-CoreUObject.dylib!UObject::ConditionalPostLoad() UE4Editor-CoreUObject.dylib!EndLoad() UE4Editor-CoreUObject.dylib!LoadPackageInternal() UE4Editor-CoreUObject.dylib!LoadPackage() UE4Editor-CoreUObject.dylib!ResolveName() UE4Editor-CoreUObject.dylib!StaticLoadObjectInternal() UE4Editor-CoreUObject.dylib!StaticLoadObject() UE4Editor-Engine.dylib!UStaticMesh* ConstructorHelpersInternal::FindOrLoadObject<UStaticMesh>() UE4Editor-Engine.dylib!ConstructorHelpers::FObjectFinder<UStaticMesh>::FObjectFinder() UE4Editor-Engine.dylib!UCameraComponent::UCameraComponent() UE4Editor-CoreUObject.dylib!UClass::CreateDefaultObject() UE4Editor-CoreUObject.dylib!FObjectInitializer::CreateDefaultSubobject() UE4Editor-CoreUObject.dylib!UObject::CreateDefaultSubobject() UE4Editor-Engine.dylib!ACameraActor::ACameraActor() UE4Editor-CoreUObject.dylib!UClass::CreateDefaultObject() UE4Editor-CoreUObject.dylib!ProcessNewlyLoadedUObjects() UE4Editor!FEngineLoop::PreInit() 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-52453 in the post.