Baking light issues

We’re trying to bake lights on our scene but we have some issues.
Can anyone help us ?

=== Lightmass crashed: ===Unhandled Exception: EXCEPTION_INT_DIVIDE_BY_ZERO
Fatal error: [File:D:\Build++UE4\Sync\Engine\Source\Programs\UnrealLightmass\Private\Lighting\LightingSystem.cpp] [Line: 1356]
Static lighting thread exception:
0x00007ff79aafb4e1 UnrealLightmass.exe!Lightmass::FStaticLightingSystem::IncomingRadianceAdaptive<Lightmass::TFinalGatherSample<2> >() ]
0x00007ff79ab11882 UnrealLightmass.exe!Lightmass::FStaticLightingSystem::CachePointIncomingRadiance() ]
0x00007ff79abd142b UnrealLightmass.exe!Lightmass::FStaticLightingSystem::ProcessCacheIndirectLightingTask() ]
0x00007ff79abc4dbc UnrealLightmass.exe!Lightmass::FStaticLightingSystem::CalculateIndirectLightingTextureMapping() ]
0x00007ff79abd3db3 UnrealLightmass.exe!Lightmass::FStaticLightingSystem::ProcessTextureMapping() ]
0x00007ff79abb6f59 UnrealLightmass.exe!Lightmass::FStaticLightingSystem::ThreadLoop() ]
0x00007ff79abb0de9 UnrealLightmass.exe!Lightmass::FMappingProcessingThreadRunnable::Run() ]
0x00007ffbf158b058 UnrealLightmass-Core.dll!UnknownFunction ]
0x00007ffbf1585a37 UnrealLightmass-Core.dll!UnknownFunction ]
0x00007ffc4a5a3034 KERNEL32.DLL!UnknownFunction ]
0x00007ffc4abe1471 ntdll.dll!UnknownFunction ]

@Dubois_simon Probably the simplest way to do this is to bin most of your scene and try and rebuild ( you can always do CTRL-Z ). Basically, bin it all, and try, it will probably work. Then bin half and try etc…

This way you can find the dodgy artifact within about 10 mins…

Bin? whats that? im having the same issue

@FAHR Bin = delete.

Two most effective methods I’ve found for getting rid of light build crashes are:

  1. Do a ‘Save as…’ and make a copy of the level. Build the light on the new level.

  2. Delete almost everything from the level and build the light. If that works, what the minimum you can remove and still build the light. Then you’re homing in on the problem…

Thanks, i think i would try to delete it all. Im importing new assets so, that wouldnt be a problem. Thanks for the help

Hey folks,

Nothing like a nice forum answer 2 years after the fact, but I was having the same issue. No answers anywhere, and no way to contact any kind of real Unreal support, so I had no choice but to keep clicking through the endless menus and drop downs in unreal until I came across something kind of obvious.

Under World settings, Lightmass, I saw that there was one of those yellow arrows indicating that something had been changed from the default and could be changed back (brilliant feature!) I clicked on that arrow next to ‘lightmass settings’ resetting that to default, then did a lighting build. No problem. NO more Divide by Zero error. No failure. I hope this helps you or anyone else who comes across this.


THAANNNKSSSS!!!,that worked perfectly!!!

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HA! YES!!! I am so pleased to be able to help!

Dude, thank you, for real, I’m going out for a beer, after 2 days of constant crashes and being stressed as hell for not being able to build . Cheers!!! :beers:

maybe this is a UV error. I have imported a large number of meshes with Datasmith. For me the error was gone when I regenerated the UV new. Simply click on all assets and right-click: “Unwrap UV”

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