Lightmass crashed with array index out of bounds

Editor version 4.7.6 on windows 7.
I have a 10 by 7 grid of 2k by 2k landscapes loaded by the tiled landscape “auto” loader. World Composition is ON and Origin rebasing is OFF. I worked around the error by moving them closer to 0,0 than they were placed by the autoloader but thought this issue should be recorded so you can fix the problem and others can possibly find a quick solution,

full dump follows:

Error === Lightmass crashed: ===
Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.7\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 679]
Array index out of bounds: 17707360 from an array of size 17707360

KERNELBASE.dll!UnknownFunction (0x000007fefd55aaad) + 0 bytes [UnknownFile:0]
UnrealLightmass-Core.dll!UnknownFunction (0x000007fecacc4544) + 0 bytes [UnknownFile:0]
UnrealLightmass-Core.dll!UnknownFunction (0x000007fecaba28c8) + 0 bytes [UnknownFile:0]
UnrealLightmass-Core.dll!UnknownFunction (0x000007fecab81075) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::TkDOPTree::SplitTriangleList() (0x000000013fe2a9f9) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::TkDOPTree::Build() (0x000000013fdde0c9) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FStaticLightingAggregateMesh::PrepareForRaytracing() (0x000000013fe19aba) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FStaticLightingSystem::FStaticLightingSystem() (0x000000013fdc0333) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::BuildStaticLighting() (0x000000013fdde951) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::LightmassMain() (0x000000013fe14f72) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!main() (0x000000013fe31950) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!__tmainCRTStartup() (0x000000013fe86467) + 0 bytes [UnknownFile:0]
kernel32.dll!UnknownFunction (0x00000000776359cd) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x000000007776b891) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x000000007776b891) + 0 bytes [UnknownFile:0]

Hello Eredin,

Would you mind providing me also with your crash logs and .dmp files generated from the crash report along with your dxdiag? To get this information to us we ask that you zip the logs and files into a folder and attach them to your response.

Thank you,

Andrew Hurley

Here is the logfile but oddly it’s not giving me a .dmp file. Can you direct me to a resource to show me how to get the rest of the information for you?
link text

No worries, I should be able to find your crash in our internal system with the information you have provided thus far. To find your crash logs and .dmp files go to your hard drive if on Windows.

Did you build your engine from source or is it the binary release version?

C:\Users\YourName\AppData\Local\Microsoft\Windows\WER\ReportQueue

Thank you,

Andrew Hurley

I am still getting this error under v4.8 p2.

Have you attempted to turn on origin rebasing and testing to see if it still occurs?

You mentioned you can avoid the crash by moving it closer to the origin so this could be what is causing the crash?