Build Lighting Crashes UE5-- Array Index Out of Bounds

Community Community & Industry Discussion
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1

New to this engine. UE5 is crashing every time I try to build lights, and only when I try to build lights. What is this error and how would I go about fixing it?

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 783] Array index out of bounds: 680322820 into an array of size 680322820

2

Im having exact same issue while “building all levels”. It freezes “Building Texture Streaming” for 5 minutes then crashes.

[2025.08.16-15.46.53:038][848]LogWindows: Error: Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 783]
[2025.08.16-15.46.53:039][848]LogWindows: Error: Array index out of bounds: 680322820 into an array of size 680322820