UE5.5 Crashed on macOS 27

General Issues and Bug Reporting (Unreal Engine)
1

Summary

UE5.5 Editor can’t launch on macOS27

What Type of Bug are you experiencing?

Editor

Steps to Reproduce

Launch Editor

Expected Result

UEEditor launches

Observed Result

Crash on launch

Affects Versions

5.5

Platform(s)

Mac

For crash reports, include your callstack

Fatal error: [File:./Runtime/Core/Private/Mac/MacPlatformProcess.cpp] [Line: 546]
FMacPlatformProcess::CreateProc: posix_spawn() failed (86, Bad CPU type in executable)

Unknown() Address = 0x185a0c308 (filename not found) [in libsystem_kernel.dylib]

2

Installing Rosetta made it launch successfully.
This was because while the Editor itself was native to Apple Silicon, the child process crashpad_handler was running as an Intel binary.