Knowledge Base: Why does my editor keep saying “LIGHTING NEEDS TO BE REBUILT”?

Development Rendering
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Why does the editor say lighting needs to be rebuilt?
Article written by Natalia C.

Anytime you add/move a static light actor or geometry it casts light onto a level, lighting will need to be rebuilt and the LIGHTING …

https://dev.epicgames.com/community/learning/knowledge-base/2mGM/unreal-engine-why-does-my-editor-keep-saying-lighting-needs-to-be-rebuilt

1 Like
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You will need to compile UnrealLightMass in your Unreal Editor Source
see
Visual Studio 2022 Preview is 64 bit and compiles and runs UE 5.0 EA approximately 20% FASTER - Compile UnrealLightMass project to Build Lighting

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But it takes forever to build especially for large worlds with buildings, landscape and vegetations.

There should be a better solution.

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here in april 2026 on UE 5.7 on mac. keep getting “lighting build failed”, errors are “World settings maps need lighting rebuilt”.