Issue: Unreal 5.6.1 Mac version downloaded from the Epic Games launcher crashes on launch after completing 10% initializing in the popup modal. See error pasted at bottom of the post. 5.7 Mac version from launcher does work thankfully.
Computer specs: Mac Studio M3 Ultra on macOS Tahoe 26.1. XCode 26.1.1 with Metal Toolchain 26.1.1 (17B54)
Workarounds I have tried:
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edit Engine/Config/Apple/Apple_SDK.json to match 5.7 https://github.com/EpicGames/UnrealEngine/blob/release/Engine/Config/Apple/Apple_SDK.json
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edit Engine/Config/Apple/Apple_SDK.json with Xcode Max version “26.9.0”, and add “26.1.0-19.1.5” to AppleVersionToLLVMVersions
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verify engine install in Epic Launcher
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install iOS target platform
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crash reporter message:
Fatal error: [File:./Runtime/Core/Private/Mac/MacPlatformProcess.cpp] [Line: 546] FMacPlatformProcess::CreateProc: posix_spawn("/Users/Shared/Epic Games/UE_5.6/Engine/Extras/ThirdPartyNotUE/libimobiledevice/Mac/idevice_id") failed (86, Bad CPU type in executable) 0x05d8d8f0 UnrealEditor-Core.dylib!FMacPlatformProcess::CreateProcInternal(char16_t const*, char16_t const*, bool, bool, bool, unsigned int*, int, char16_t const*, void*, void*, void*) [UnknownFile]) 0x05d8c37c UnrealEditor-Core.dylib!FMacPlatformProcess::ExecProcess(char16_t const*, char16_t const*, int*, FString*, FString*, char16_t const*, bool) [UnknownFile]) 0x8d422e1c UnrealEditor-IOSTargetPlatformControls.dylib!FDeviceQueryTask::QueryDevices() [UnknownFile]) 0x8d421f70 UnrealEditor-IOSTargetPlatformControls.dylib!FDeviceQueryTask::Run() [UnknownFile]) 0x05c469e8 UnrealEditor-Core.dylib!FRunnableThreadPThread::Run() [UnknownFile]) 0x05bea130 UnrealEditor-Core.dylib!FRunnableThreadPThread::_ThreadProc(void*) [UnknownFile]) 0x993d9c08 libsystem_pthread.dylib!_pthread_start() [UnknownFile]) 0x993d4ba8 libsystem_pthread.dylib!thread_start() [UnknownFile])