Unreal 5.6.1 Mac version downloaded from the Epic Games launcher crashes on launch after completing 10% initializing in the popup modal

diddlyDixon · November 22, 2025, 5:16pm

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:

edit Engine/Config/Apple/Apple_SDK.json to match 5.7 https://github.com/EpicGames/UnrealEngine/blob/release/Engine/Config/Apple/Apple_SDK.json
edit Engine/Config/Apple/Apple_SDK.json with Xcode Max version “26.9.0”, and add “26.1.0-19.1.5” to AppleVersionToLLVMVersions
verify engine install in Epic Launcher
install iOS target platform

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])

Eddy_Gto · November 24, 2025, 7:52pm

I’m having the same issue.

I have tried verifying, reinstalling, clear settings, give permissions in settings. And nothing has fixed it.

Lneuberger · November 29, 2025, 9:55pm

Similar issue here. I can open it and use it to a point but rotating an object crashes it and so does importing my textures. It is completely unusable but worked fine on my last Mac.

gundz · January 23, 2026, 6:10pm

Hello,

So the trick, is to download the unreal sources from github.

Then checkout branch 5.6 (cdda65cecacd9a1278020925c357bf4cc0b17e8c currently for me)

Do ./Setup.bat to download the binary files (did it from windows, but should work the same for mac)

all this will take a while depending on your connection.

Then make a backup (or zip) of “/Users/Shared/Epic Games/UE_5.6/Engine/Extras/ThirdPartyNotUE/libimobiledevice” (just in case)

Remove all the files inside “/Users/Shared/Epic Games/UE_5.6/Engine/Extras/ThirdPartyNotUE/libimobiledevice”

and replace with the one from the unreal sources (they are here “[SourceRepoDir]\Engine\Extras\ThirdPartyNotUE\libimobiledevice\Mac”)

This worked for me.

ShawKing · January 27, 2026, 3:17pm

Tried your method, It didn’t work.
Update : Gpt Helped me fix it.

Solution:

Unreal Engine 5.6 iOS Fix on Apple Silicon (ARM64)

This guide fixes the following Unreal Engine 5.6 crash on Apple Silicon Macs without using Rosetta and with full iOS support enabled:

FMacPlatformProcess::CreateProc
Bad CPU type in executable (86)

Cause: Unreal Engine 5.6 ships an Intel-only (x86_64) idevice_id binary, which crashes when Unreal runs natively on ARM64.

Solution Overview

Replace Unreal’s bundled idevice_id with an ARM64 version from Homebrew and codesign it so Unreal can execute it safely.

This keeps:

Native ARM Unreal Editor
Full iOS device detection
iOS packaging & deployment

1. Install ARM64 libimobiledevice (Homebrew)

brew install libimobiledevice

Verify the binary path:

which idevice_id

Expected:

/opt/homebrew/bin/idevice_id

Verify architecture:

file /opt/homebrew/bin/idevice_id

Expected:

Mach-O 64-bit executable arm64

2. Navigate to Unreal’s libimobiledevice Folder

cd "/Users/Shared/Epic Games/UE_5.6/Engine/Extras/ThirdPartyNotUE/libimobiledevice/Mac"

Confirm Unreal’s bundled binary is Intel-only:

file idevice_id

Expected:

Mach-O 64-bit executable x86_64

3. Backup Unreal’s Original Binary (Important)

mv idevice_id idevice_id_x86_64_backup

4. Replace with ARM64 Homebrew Binary

cp /opt/homebrew/bin/idevice_id .
chmod +x idevice_id

Verify:

file idevice_id

Expected:

Mach-O 64-bit executable arm64

5. Codesign the Binary (CRITICAL)

Unreal will fail to spawn unsigned binaries.

codesign --force --deep --sign - idevice_id

Verify:

codesign -vv idevice_id

There should be no errors.

6. Test idevice_id Manually

Plug in your iPhone, unlock it, and trust the Mac.

./idevice_id -l

Expected:

Lists device UDID → perfect
Empty output → still fine
Crash → something is wrong

7. Launch Unreal Engine (ARM-native)

Launch Unreal Editor normally (do NOT use Rosetta).

Expected Result

No “Bad CPU type in executable” crash
iOS platform loads correctly
iOS devices detected
Packaging works

After Unreal Engine Updates (Important)

Epic updates may overwrite the binary.

Use this one-liner to reapply the fix:

cp /opt/homebrew/bin/idevice_id \
"/Users/Shared/Epic Games/UE_5.6/Engine/Extras/ThirdPartyNotUE/libimobiledevice/Mac/idevice_id" && \
codesign --force --deep --sign - \
"/Users/Shared/Epic Games/UE_5.6/Engine/Extras/ThirdPartyNotUE/libimobiledevice/Mac/idevice_id"

Notes

This is a known Unreal Engine 5.6 issue on Apple Silicon
The Homebrew libimobiledevice tools are ARM-native and safe to use
Same fix applies to other tools if needed:
- ideviceinfo
- idevicesyslog
- iproxy

Final Status

Native ARM Unreal Editor
iOS support enabled
No Rosetta required
Stable workflow

File: UE5.6_AppleSilicon_iOS_libimobiledevice_Fix.md