This is a common crash on Mac that occurs in the 4.16 release. This appears similar to [Link Removed], which was closed with the 4.13 release.
Users have not provided descriptions. Many (but not all) of the crashes occur when running a commandlet.
Callstack from Log
LogFileServer:Warning: Unreal Network Http File Server starting up... LogMac:Error: appError called: Assertion failed: Assertion failed: [File:/Users/build/Build/++UE4+Release-4.16+Compile/Sync/Engine/Source/Runtime/NetworkFileSystem/Private/NetworkFileServerHttp.cpp] [Line: 159] Could not create a libwebsocket content for port : 41898 LogMac: === Critical error: === SIGSEGV: invalid attempt to access memory at address 0x3 LogMac: FGenericPlatformMisc::RaiseException(unsigned int) Address = 0x37d7f1b (filename not found) [in UE4Editor-Core.dylib] FOutputDeviceMacError::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&) Address = 0x39d3d7f (filename not found) [in UE4Editor-Core.dylib] FOutputDevice::Logf(wchar_t const*, ...) Address = 0x3ab488d (filename not found) [in UE4Editor-Core.dylib] FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...) Address = 0x3a1aafe (filename not found) [in UE4Editor-Core.dylib] FNetworkFileServerHttp::Init() Address = 0x1870c6a2 (filename not found) [in UE4Editor-NetworkFileSystem.dylib] FRunnableThreadPThread::Run() Address = 0x3859458 (filename not found) [in UE4Editor-Core.dylib] FRunnableThreadPThread::_ThreadProc(void*) Address = 0x38155f0 (filename not found) [in UE4Editor-Core.dylib] _pthread_body() Address = 0xcef0493b (filename not found) [in libsystem_pthread.dylib] _pthread_body() Address = 0xcef04887 (filename not found) [in libsystem_pthread.dylib] thread_start() Address = 0xcef0408d (filename not found) [in libsystem_pthread.dylib]
repro steps currently unknown
SEGV_MAPERR at 0x3 UE4Editor-NetworkFileSystem.dylib!FNetworkFileServerHttp::Init() UE4Editor-Core.dylib!FRunnableThreadPThread::Run() UE4Editor-Core.dylib!FRunnableThreadPThread::_ThreadProc() 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-46409 in the post.