Crash on lighting build

I am getting a crash when attempting to run a lighting build in a custom build of the editor. An assert fires when the engine attempts to get the swarm interface, giving the following output:

Assertion failed: &Swarm != NULL [File:C:\Jenkins\workspace\editor_unreal\Engine\Source\Editor\UnrealEd\Private\Lightmass\Lightmass.cpp] [Line: 2571]

UE4Editor_Core!FDebug::AssertFailed()
UE4Editor_UnrealEd!FLightmassProcessor::FLightmassProcessor()
UE4Editor_UnrealEd!FStaticLightingSystem::CreateLightmassProcessor()
UE4Editor_UnrealEd!FStaticLightingSystem::BeginLightmassProcess()
UE4Editor_UnrealEd!FStaticLightingManager::CreateStaticLightingSystem()
UE4Editor_UnrealEd!UEditorEngine::BuildLighting()
UE4Editor_UnrealEd!FEditorBuildUtils::EditorBuild()
UE4Editor_LevelEditor!FLevelEditorActionCallbacks::BuildLightingOnly_Execute()
UE4Editor_LevelEditor!?ExecuteIfSafe@?$TBaseStaticDelegateInstance@$$A6AXXZ$$V@@UEBA_NXZ()
UE4Editor_Slate!FUICommandList::ExecuteAction()
UE4Editor_Slate!SMenuEntryBlock::OnClicked()
UE4Editor_Slate!SMenuEntryBlock::OnMenuItemButtonClicked()
UE4Editor_Slate!?Execute@?$TBaseSPMethodDelegateInstance@$0A@VSMenuEntryBlock@@$0A@$$A6A?AVFReply@@XZ$$V@@UEBA?AVFReply@@XZ()
UE4Editor_Slate!SButton::OnMouseButtonUp()
UE4Editor_Slate!SMenuEntryButton::OnMouseButtonUp()
UE4Editor_Slate!SButton::FArguments::OnClicked<SWindowTitleBar>()
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent()
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent()
UE4Editor_Slate!FSlateApplication::OnMouseUp()
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage()
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage()
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage()
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc()
user32
user32
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages()
UE4Editor_Cmd!FEngineLoop::Tick()
UE4Editor_Cmd!GuardedMain()
UE4Editor_Cmd!GuardedMainWrapper()
UE4Editor_Cmd!WinMain()
UE4Editor_Cmd!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283]
kernel32
ntdll

I am using a custom build graph script to package the editor, as far as I can tell everything is compiled and included correctly, however the error refers to a path used by my jenkins build process which shouldn’t be the case as I have built this manually on my own machine.

Any help here would be appreciated.

Check to make sure that
\Engine\Binaries\DotNET\SwarmInterface.dll
exists.

If not, then it is possible that this may have been a case of deleted binaries that are installed when running Setup.bat, but are not built by the solution.