# lightmass crashing **URL:** \ **Category:** Programming & Scripting\ **Tags:** Lightmass, lightmass-crash, unreal-engine, Lightmap, Rendering, question\ **Created:** [June 13, 2025, 8:31pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552 "2025-06-13T20:31:06Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 13, 2025, 8:31pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/1 "2025-06-13T20:31:06Z")
i keep getting this ■■■■ crash i tried to force log and go through every line of the log but couldnt find any fix Assertion failed: TextureUniformBase [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\Materials\HLSLMaterialTranslator.cpp] [Line: 4521] TexInputType is 1073741824, but missing FMaterialUniformExpression ---
**Author:** ![Mind-Brain](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/mind-brain/32/906573_2.png) [@Mind-Brain](https://forums.unrealengine.com/u/Mind-Brain)\ **Post date:** [June 13, 2025, 8:49pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/2 "2025-06-13T20:49:33Z")
Hey @User-0befe8ef7d! This seems to be an issue with a source file. First, try doing a validation check of the Engine version you’re using. ![image](https://d3kjluh73b9h9o.cloudfront.net/original/4X/f/b/5/fb585ae45c0d8e4242ed4f5c0417e32934155152.png) I would suggest trying a different version as well but if you’re on 5.6 you literally can’t migrate it… Hope that helps! ---
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 13, 2025, 9:13pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/3 "2025-06-13T21:13:52Z")
its not a source file problem bcz if i bake another level from the same project everything goes fine and even if i remove everything from the problematic scene and place a random cube it bakes its a material problem im using megascans materials and materials taken from the deleric corridor sample of quixel ---
**Author:** ![Mind-Brain](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/mind-brain/32/906573_2.png) [@Mind-Brain](https://forums.unrealengine.com/u/Mind-Brain)\ **Post date:** [June 13, 2025, 11:00pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/4 "2025-06-13T23:00:13Z")
> [@User-0befe8ef7d](#): > > build++UE5\Sync\Engine\Source\Runtime\Engine\Private\Materials This address in your project states that the material issue in question is part of the Engine (line 4521 of the .cpp file "HLSLMaterialTranslator). Either the material itself is broken (which means too bad use something else if you got it from Megascans) or the .cpp file is corrupted, which an engine verify should theoretically fix. The problem can literally only be: 1. The material 2. The .cpp file HLSL Material Translator 3. Their communication lines You could try deleting and redownloading it from Quixel as well. Regardless, it’s corruption, so the only way to fix it is to refresh and hopefully get an uncorrupted file. 🙂 ---
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 14, 2025, 11:19am UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/5 "2025-06-14T11:19:47Z")
okey i verified the integrity of engine files and nothing happened so its basically a material problem but how can i debug which material is causing the crash ---
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 14, 2025, 5:53pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/6 "2025-06-14T17:53:25Z")
okey i think i found the problem where its from these 9 master materials either all of them or one of them cz when i delete them i can bake just fine without any crash [mats.zip](https://forums.unrealengine.com/uploads/short-url/6RluD4CRZdnQNFoMGnkYNRtllGu.zip) (534.2 KB) ---
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 15, 2025, 1:58pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/7 "2025-06-15T13:58:38Z")
aight found the problem its caused by m\_walls material [m\_walls posted by anonymous | blueprintUE | PasteBin For Unreal Engine](https://blueprintue.com/blueprint/b306x3b-/) but idk which part is causing it ---
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 16, 2025, 2:43pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/8 "2025-06-16T14:43:56Z")
UPDATE : the crash is caused by the base color which is connected to thousand of other nodes and functions idk if i can test out with every single node ---
**Author:** ![Mind-Brain](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/mind-brain/32/906573_2.png) [@Mind-Brain](https://forums.unrealengine.com/u/Mind-Brain)\ **Post date:** [June 16, 2025, 8:37pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/9 "2025-06-16T20:37:16Z")
Interesting. Because the base color is just… part of any material. Like it’s not sampling from anywhere- which screams “Corrupted.” I’m going to try to download it from bridge and see what I can figure out a manual solution. What are the specific megascans you’re using? Give me any information you can so I can actually find it in Quixel bridge. “Derelict Corridor” is giving nothing that I can find. ☹ ---
**Author:** ![User-0befe8ef7d](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@User-0befe8ef7d](https://forums.unrealengine.com/u/User-0befe8ef7d)\ **Post date:** [June 22, 2025, 3:33pm UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/10 "2025-06-22T15:33:36Z")
late reply but i found out that deleting the paint node solved the problem ---
**Author:** ![MikhailSAD](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@MikhailSAD](https://forums.unrealengine.com/u/MikhailSAD)\ **Post date:** [January 3, 2026, 7:53am UTC](https://forums.unrealengine.com/t/lightmass-crashing/2555552/11 "2026-01-03T07:53:58Z")
In the paint node, you need to replace **“Mesh Paint Texture Replace”** with **“LightmassReplace”** for it to work correctly.