Users on the forums are hitting a crash on their initial launch of the engine into dx12. There is currently a workaround to load into the project with dx11 first, compile shaders, then youre fine to load into dx12. Very similar to an issue reported earlier [Link Removed].
Result: Editor crashes on start
Frequency: 3/3
=== Critical error: === Assertion failed: ShaderRef != 0 && *ShaderRef != nullptr [File:D:\Build\++UE4\Sync\Engine\Source\Runtime\RenderCore\Public\Shader.h] [Line: 1887] Failed to find shader type FBuildRectLightMipTreeCS in Platform PCD3D_SM5 [Callstack] 0x00007fff0c455549 KERNELBASE.dll!UnknownFunction [] [Callstack] 0x00007ffeae5b1607 UE4Editor-Core.dll!ReportAssert() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowsplatformcrashcontext.cpp:551] [Callstack] 0x00007ffeae5b3db7 UE4Editor-Core.dll!FWindowsErrorOutputDevice::Serialize() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowserroroutputdevice.cpp:79] [Callstack] 0x00007ffeae3c720a UE4Editor-Core.dll!FOutputDevice::LogfImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:71] [Callstack] 0x00007ffeae34f367 UE4Editor-Core.dll!FDebug::AssertFailed() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:440] [Callstack] 0x00007ffeae34f9f9 UE4Editor-Core.dll!FDebug::CheckVerifyFailedImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:418] [Callstack] 0x00007ffe9c828ed8 UE4Editor-Engine.dll!DispatchCheckVerify<void,<lambda_27e8da042b46d77eec5127ab21bf535b> >() [d:\build\++ue4\sync\engine\source\runtime\core\public\misc\assertionmacros.h:161] [Callstack] 0x00007ffe9b667e5c UE4Editor-Engine.dll!BuildRectLightMipTree() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\rectlightcomponent.cpp:389] [Callstack] 0x00007ffe9b6ab9b0 UE4Editor-Engine.dll!URectLightComponent::UpdateRayTracingData() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\rectlightcomponent.cpp:37] [Callstack] 0x00007ffe9b65927c UE4Editor-Engine.dll!URectLightComponent::URectLightComponent() [d:\build\++ue4\sync\engine\source\runtime\engine\private\components\rectlightcomponent.cpp:69] [Callstack] 0x00007ffeaebf612f UE4Editor-CoreUObject.dll!UClass::CreateDefaultObject() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\class.cpp:3076] [Callstack] 0x00007ffeaee05e77 UE4Editor-CoreUObject.dll!FObjectInitializer::CreateDefaultSubobject() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:3656] [Callstack] 0x00007ffeaed63bb8 UE4Editor-CoreUObject.dll!UObject::CreateDefaultSubobject() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:107] [Callstack] 0x00007ffe9ba2b451 UE4Editor-Engine.dll!ALight::ALight() [d:\build\++ue4\sync\engine\source\runtime\engine\private\light.cpp:19] [Callstack] 0x00007ffe9be62011 UE4Editor-Engine.dll!ARectLight::ARectLight() [d:\build\++ue4\sync\engine\source\runtime\engine\private\rectlight.cpp:7] [Callstack] 0x00007ffeaebf612f UE4Editor-CoreUObject.dll!UClass::CreateDefaultObject() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\class.cpp:3076] [Callstack] 0x00007ffeaee30f96 UE4Editor-CoreUObject.dll!UObjectLoadAllCompiledInDefaultProperties() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:789] [Callstack] 0x00007ffeaee1ed8f UE4Editor-CoreUObject.dll!ProcessNewlyLoadedUObjects() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:869] [Callstack] 0x00007ff68023cf44 UE4Editor.exe!FEngineLoop::PreInit() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2359] [Callstack] 0x00007ff680235377 UE4Editor.exe!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:129] [Callstack] 0x00007ff6802355ca UE4Editor.exe!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:145] [Callstack] 0x00007ff68024315c UE4Editor.exe!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:275] [Callstack] 0x00007ff680245b7e UE4Editor.exe!__scrt_common_main_seh() [d:\agent\_work\3\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288] [Callstack] 0x00007fff0fa581f4 KERNEL32.DLL!UnknownFunction [] [Callstack] 0x00007fff0fe4a251 ntdll.dll!UnknownFunction []
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-71810 in the post.