Lightmass crashed

Im new to UE4 I been going thru a tutorial now I create a scene and have 2 light on the scene when I run build light the Lightmass crashed Message Log see below. What can be wrong here???
Thank you all

Error <None> === Lightmass crashed: ===
Assertion failed: Importer.ImportData((FBaseMaterialData*)this) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.8\Engine\Source\Programs\UnrealLightmass\Private\ImportExport\Material.cpp] [Line: 14]

KERNELBASE.dll {0x00007ffa63e68b9c} + 0 bytes
UnrealLightmass-Core.dll {0x00007ffa1b5be6bf} + 0 bytes
UnrealLightmass-Core.dll {0x00007ffa1b4a1058} + 0 bytes
UnrealLightmass-Core.dll {0x00007ffa1b482098} + 0 bytes
UnrealLightmass.exe!Lightmass::FMaterial::Import() {0x00007ff6ca29503a} + 0 bytes
UnrealLightmass.exe!Lightmass::FLightmassImporter::ConditionalImportObject<Lightmass::FMaterial,TMap<FGuid,Lightmass::FMaterial * __ptr64,FDefaultSetAllocator,TDefaultMapKeyFuncs<FGuid,Lightmass::FMaterial * __ptr64,0> > >() {0x00007ff6ca229dbc} + 0 bytes
UnrealLightmass.exe!Lightmass::FStaticLightingMesh::Import() {0x00007ff6ca297c76} + 0 bytes
UnrealLightmass.exe!Lightmass::FStaticMeshStaticLightingMesh::Import() {0x00007ff6ca3025da} + 0 bytes
UnrealLightmass.exe!Lightmass::FLightmassImporter::ImportObjectArray<Lightmass::FStaticMeshStaticLightingMesh,TMap<FGuid,Lightmass::FStaticMeshStaticLightingMesh * __ptr64,FDefaultSetAllocator,TDefaultMapKeyFuncs<FGuid,Lightmass::FStaticMeshStaticLightingMesh * __ptr64,0> > >() {0x00007ff6ca230d03} + 0 bytes
UnrealLightmass.exe!Lightmass::FScene::Import() {0x00007ff6ca2965b2} + 0 bytes
UnrealLightmass.exe!Lightmass::FLightmassImporter::ImportScene() {0x00007ff6ca2982d0} + 0 bytes
UnrealLightmass.exe!Lightmass::BuildStaticLighting() {0x00007ff6ca26299f} + 0 bytes
UnrealLightmass.exe!Lightmass::LightmassMain() {0x00007ff6ca29f3b8} + 0 bytes
UnrealLightmass.exe!main() {0x00007ff6ca2bd94f} + 0 bytes
UnrealLightmass.exe!__tmainCRTStartup() {0x00007ff6ca31950b} + 0 bytes
KERNEL32.DLL {0x00007ffa65f913d2} + 0 bytes
ntdll.dll {0x00007ffa67c65444} + 0 bytes
ntdll.dll {0x00007ffa67c65444} + 0 bytes

Ok so no one can give me a idea here…I been talk that this forum are really good in helping other…So who can give me some answers here
Thank you

-do you build on preview?
-do you get the same crash when you build a template map?
-is this the crash log from “swarm” -> the little yellow icon in the systray - open it during the light build process - take a look at the log file
-add a lightmass importance volume
-which lights do you use in your level?
-are the set to “static”? :slight_smile:

Hello I want to thank you for you input here first. Ok I do build on the preview, I have volume process in the map, I have a spot light and a point light both are static. the msg I place here is from message log lighting Results. and yes is from the yellow icon it show in the systray when is running the lightmass.
Thank you again
By the way I run other map and I have no crash so I suspect is the map im using for this version…i will check into that also. and I will post it here in case other run into a similar issue.


I’m sort of new to UE 4.8. I have quite a large scene that I am trying to build. I keep getting the following error when trying to build the lighting. I have dropped the foliage lightmap settings to 8 for both the static meshes I am using to distribute.

How do I solve this issue?

Hope someone can help.

Thank you in advance.