UBT missing: problem compiling UE4 source code in mac 10.12.6

Hi,

im having problems compiling UE from source here is my environment details:

OSX version: 10.12.6
UE4 source code version: 4.18
Xcode version: 9.2
Mono: bundled mono from UE

i followed what is indicated in the readme but a stack trace appears as follows:

Setting up Unreal Engine 4 project files...

Setting up Mono
Stacktrace:

  at <unknown> <0xffffffff>
  at (wrapper managed-to-native) System.Reflection.Assembly.InternalGetAssemblyName (string,System.Reflection.AssemblyName) <0xffffffff>
  at System.Reflection.AssemblyName.GetAssemblyName (string) <0x00043>
  at Microsoft.Build.Tasks.AssemblyResolver.TryGetAssemblyNameFromFile (string,System.Reflection.AssemblyName&) <0x0009f>
  at Microsoft.Build.Tasks.ResolveAssemblyReference.ResolveAssemblyFiles () <0x001cb>
  at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute () <0x00253>
  at Microsoft.Build.BuildEngine.TaskEngine.Execute () <0x00021>
  at Microsoft.Build.BuildEngine.BuildTask.Execute () <0x0035c>
  at Microsoft.Build.BuildEngine.TaskBatchingImpl.Execute (Microsoft.Build.BuildEngine.IBuildTask,Microsoft.Build.BuildEngine.TaskExecutionMode) <0x00072>
  at Microsoft.Build.BuildEngine.TaskBatchingImpl.Build (Microsoft.Build.BuildEngine.IBuildTask,Microsoft.Build.BuildEngine.TaskExecutionMode,bool&) <0x0007e>
  at Microsoft.Build.BuildEngine.TargetBatchingImpl.RunTargetWithBucket (System.Collections.Generic.Dictionary`2<string, Microsoft.Build.BuildEngine.BuildItemGroup>,Microsoft.Build.BuildEngine.Target,bool&) <0x002f1>
  at Microsoft.Build.BuildEngine.TargetBatchingImpl.Run (Microsoft.Build.BuildEngine.Target,bool&) <0x0012e>
  at Microsoft.Build.BuildEngine.TargetBatchingImpl.Build (Microsoft.Build.BuildEngine.Target,bool&) <0x0006a>
  at Microsoft.Build.BuildEngine.Target.DoBuild (bool&) <0x00073>
  at Microsoft.Build.BuildEngine.Target.BuildActual (string,bool&) <0x00282>
  at Microsoft.Build.BuildEngine.Target.Build (string,string,bool&) <0x00217>
  at Microsoft.Build.BuildEngine.Target.BuildOtherTargets (System.Collections.Generic.IEnumerable`1<string>,System.Action`1<string>,bool&) <0x0012b>
  at Microsoft.Build.BuildEngine.Target.BuildDependencies (bool&) <0x001fc>
  at Microsoft.Build.BuildEngine.Target.BuildActual (string,bool&) <0x0023c>
  at Microsoft.Build.BuildEngine.Target.Build (string,string,bool&) <0x00217>
  at Microsoft.Build.BuildEngine.Target.BuildOtherTargets (System.Collections.Generic.IEnumerable`1<string>,System.Action`1<string>,bool&) <0x0012b>
  at Microsoft.Build.BuildEngine.Target.BuildDependencies (bool&) <0x001fc>
  at Microsoft.Build.BuildEngine.Target.BuildActual (string,bool&) <0x0023c>
  at Microsoft.Build.BuildEngine.Target.Build (string,string,bool&) <0x00217>
  at Microsoft.Build.BuildEngine.Target.BuildOtherTargets (System.Collections.Generic.IEnumerable`1<string>,System.Action`1<string>,bool&) <0x0012b>
  at Microsoft.Build.BuildEngine.Target.BuildDependencies (bool&) <0x001fc>
  at Microsoft.Build.BuildEngine.Target.BuildActual (string,bool&) <0x0023c>
  at Microsoft.Build.BuildEngine.Target.Build (string,string,bool&) <0x00217>
  at Microsoft.Build.BuildEngine.Target.Build (string) <0x0002d>
  at Microsoft.Build.BuildEngine.Project.BuildTarget (string,System.Collections.IDictionary) <0x00108>
  at Microsoft.Build.BuildEngine.Project.BuildInternal (string[],System.Collections.IDictionary,Microsoft.Build.BuildEngine.BuildSettings) <0x002cf>
  at Microsoft.Build.BuildEngine.Project.Build (string[],System.Collections.IDictionary,Microsoft.Build.BuildEngine.BuildSettings) <0x00144>
  at Microsoft.Build.BuildEngine.Engine.BuildProjectFileInternal (string,string[],Microsoft.Build.BuildEngine.BuildPropertyGroup,System.Collections.IDictionary,Microsoft.Build.BuildEngine.BuildSettings,string) <0x00474>
  at Microsoft.Build.BuildEngine.Engine.BuildProjectFile (string,string[],Microsoft.Build.BuildEngine.BuildPropertyGroup,System.Collections.IDictionary,Microsoft.Build.BuildEngine.BuildSettings,string) <0x00088>
  at Mono.XBuild.CommandLine.MainClass.Execute () <0x00c83>
  at Mono.XBuild.CommandLine.MainClass.Main (string[]) <0x00053>
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff>

Native stacktrace:

	0   mono                                0x000000010ea054ae mono_handle_native_sigsegv + 334
	1   mono                                0x000000010eae037e sigabrt_signal_handler + 158
	2   libsystem_platform.dylib            0x00007fffc3c27b3a _sigtramp + 26
	3   ???                                 0x00007f848b40ab2c 0x0 + 140207248681772
	4   libsystem_c.dylib                   0x00007fffc3aac420 abort + 129
	5   mono                                0x000000010ec99ad3 monoeg_log_default_handler + 211
	6   mono                                0x000000010ec999e2 monoeg_g_logv + 114
	7   mono                                0x000000010ec99de4 monoeg_assertion_message + 356
	8   mono                                0x000000010eb6ff34 mono_metadata_string_heap + 100
	9   mono                                0x000000010eb3cd78 mono_image_load_names + 88
	10  mono                                0x000000010eb3d326 do_mono_image_load + 278
	11  mono                                0x000000010eb3d85f do_mono_image_open + 671
	12  mono                                0x000000010eb3c310 mono_image_open_full + 336
	13  mono                                0x000000010eb3d88f mono_image_open + 31
	14  mono                                0x000000010eb2fd5c ves_icall_System_Reflection_Assembly_InternalGetAssemblyName + 124
	15  ???                                 0x0000000111a5a7ef 0x0 + 4591036399
	16  ???                                 0x0000000111a5c1cc 0x0 + 4591043020
	17  ???                                 0x0000000111a01c92 0x0 + 4590673042
	18  ???                                 0x00000001119fb243 0x0 + 4590645827
	19  ???                                 0x00000001119f8712 0x0 + 4590634770
	20  ???                                 0x00000001119f83af 0x0 + 4590633903
	21  ???                                 0x00000001119f6b3b 0x0 + 4590627643
	22  ???                                 0x00000001119f68b4 0x0 + 4590626996
	23  ???                                 0x00000001119f5ca3 0x0 + 4590623907
	24  ???                                 0x00000001119f57e8 0x0 + 4590622696
	25  ???                                 0x00000001119f672c 0x0 + 4590626604
	26  ???                                 0x00000001119f64ad 0x0 + 4590625965

Debug info from gdb:

(lldb) command source -s 0 '/tmp/mono-gdb-commands.vSEyVO'
Executing commands in '/tmp/mono-gdb-commands.vSEyVO'.
(lldb) process attach --pid 12526
Process 12526 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    frame #0: 0x00007fffc3b473ee libsystem_kernel.dylib`__wait4 + 10
libsystem_kernel.dylib`__wait4:
->  0x7fffc3b473ee <+10>: jae    0x7fffc3b473f8            ; <+20>
    0x7fffc3b473f0 <+12>: movq   %rax, %rdi
    0x7fffc3b473f3 <+15>: jmp    0x7fffc3b3fcd4            ; cerror
    0x7fffc3b473f8 <+20>: retq   
Target 0: (mono) stopped.

Executable module set to "/Users/user/UnrealEngine/Engine/Build/BatchFiles/Mac/../../../Binaries/ThirdParty/Mono/Mac/bin/mono".
Architecture set to: x86_64h-apple-macosx.
(lldb) thread list
Process 12526 stopped
* thread #1: tid = 0x1080b, 0x00007fffc3b473ee libsystem_kernel.dylib`__wait4 + 10, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
  thread #2: tid = 0x1080c, 0x00007fffc3b3f386 libsystem_kernel.dylib`semaphore_wait_trap + 10
  thread #3: tid = 0x1080d, 0x00007fffc3b4744e libsystem_kernel.dylib`__workq_kernreturn + 10
  thread #4: tid = 0x1080e, 0x00007fffc3b4744e libsystem_kernel.dylib`__workq_kernreturn + 10
  thread #5: tid = 0x1080f, 0x00007fffc3b4744e libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread backtrace all
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
  * frame #0: 0x00007fffc3b473ee libsystem_kernel.dylib`__wait4 + 10
    frame #1: 0x000000010ea055d2 mono`mono_handle_native_sigsegv + 626
    frame #2: 0x000000010eae037e mono`sigabrt_signal_handler + 158
    frame #3: 0x00007fffc3c27b3a libsystem_platform.dylib`_sigtramp + 26
    frame #4: 0x00007fffc3b46d43 libsystem_kernel.dylib`__pthread_kill + 11
    frame #5: 0x00007fffc3c34457 libsystem_pthread.dylib`pthread_kill + 90
    frame #6: 0x00007fffc3aac420 libsystem_c.dylib`abort + 129
    frame #7: 0x000000010ec99ad3 mono`monoeg_log_default_handler + 211
    frame #8: 0x000000010ec999e2 mono`monoeg_g_logv + 114
    frame #9: 0x000000010ec99de4 mono`monoeg_assertion_message + 356
    frame #10: 0x000000010eb6ff34 mono`mono_metadata_string_heap + 100
    frame #11: 0x000000010eb3cd78 mono`mono_image_load_names + 88
    frame #12: 0x000000010eb3d326 mono`do_mono_image_load + 278
    frame #13: 0x000000010eb3d85f mono`do_mono_image_open + 671
    frame #14: 0x000000010eb3c310 mono`mono_image_open_full + 336
    frame #15: 0x000000010eb3d88f mono`mono_image_open + 31
    frame #16: 0x000000010eb2fd5c mono`ves_icall_System_Reflection_Assembly_InternalGetAssemblyName + 124
    frame #17: 0x0000000111a5a7ef
    frame #18: 0x0000000111a5c1cc
    frame #19: 0x0000000111a01c92
    frame #20: 0x00000001119fb243
    frame #21: 0x00000001119f8712
    frame #22: 0x00000001119f83af
    frame #23: 0x00000001119f6b3b
    frame #24: 0x00000001119f68b4
    frame #25: 0x00000001119f5ca3
    frame #26: 0x00000001119f57e8
    frame #27: 0x00000001119f672c
    frame #28: 0x00000001119f64ad
  thread #2
    frame #0: 0x00007fffc3b3f386 libsystem_kernel.dylib`semaphore_wait_trap + 10
    frame #1: 0x000000010ec6d77a mono`mono_sem_wait + 26
    frame #2: 0x000000010ebf38f4 mono`finalizer_thread + 196
    frame #3: 0x000000010ebc00e4 mono`start_wrapper_internal + 740
    frame #4: 0x000000010ebbfdf1 mono`start_wrapper + 33
    frame #5: 0x000000010ec75551 mono`inner_start_thread + 577
    frame #6: 0x000000010ec91d6e mono`GC_start_routine + 110
    frame #7: 0x00007fffc3c3193b libsystem_pthread.dylib`_pthread_body + 180
    frame #8: 0x00007fffc3c31887 libsystem_pthread.dylib`_pthread_start + 286
    frame #9: 0x00007fffc3c3108d libsystem_pthread.dylib`thread_start + 13
  thread #3
    frame #0: 0x00007fffc3b4744e libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fffc3c3148e libsystem_pthread.dylib`_pthread_wqthread + 1023
    frame #2: 0x00007fffc3c3107d libsystem_pthread.dylib`start_wqthread + 13
  thread #4
    frame #0: 0x00007fffc3b4744e libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fffc3c31621 libsystem_pthread.dylib`_pthread_wqthread + 1426
    frame #2: 0x00007fffc3c3107d libsystem_pthread.dylib`start_wqthread + 13
  thread #5
    frame #0: 0x00007fffc3b4744e libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fffc3c31621 libsystem_pthread.dylib`_pthread_wqthread + 1426
    frame #2: 0x00007fffc3c3107d libsystem_pthread.dylib`start_wqthread + 13
(lldb) detach

=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

Process 12526 detached
(lldb) quit
Cannot open assembly '../../../Binaries/DotNET/UnrealBuildTool.exe': No such file or directory. 

it appears that it wasn’t able to compile the UnrealBuildTool successfully. I am stuck on this error for quite some time now. any help would be greatly appreciated. Thanks.