# Editor crash (unhandled assert) when changing blend mode on a material assigned to a Nanite static mesh

**URL:** <https://forums.unrealengine.com/t/editor-crash-unhandled-assert-when-changing-blend-mode-on-a-material-assigned-to-a-nanite-static-mesh/2764048>\
**Category:** Issues and Bug Reporting (Unreal Engine)\
**Tags:** unreal-engine, closed\
**Created:** [September 9, 2026, 6:12pm UTC](https://forums.unrealengine.com/t/editor-crash-unhandled-assert-when-changing-blend-mode-on-a-material-assigned-to-a-nanite-static-mesh/2764048 "2026-09-09T18:12:48Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Zeto\_Tabori77](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Zeto\_Tabori77](https://forums.unrealengine.com/u/Zeto_Tabori77)\
**Post date:** [September 9, 2026, 6:12pm UTC](https://forums.unrealengine.com/t/editor-crash-unhandled-assert-when-changing-blend-mode-on-a-material-assigned-to-a-nanite-static-mesh/2764048/1 "2026-09-09T18:12:48Z")

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### Summary

Changing a material’s Blend Mode crashes the editor when that material is currently assigned to a Nanite-enabled static mesh (visible in the level or in the Material Editor preview). The engine correctly logs a warning that the blend mode is unsupported on Nanite, but then proceeds into a Lumen scene card capture path that asserts instead of failing gracefully.

### What Type of Bug are you experiencing?

AI

### Steps to Reproduce

Create or use a static mesh with Nanite enabled.  
Assign a material to it (in the level, or set as the Material Editor’s preview mesh).  
Open the material and change its Blend Mode.  
Editor crashes immediately.

### Expected Result

Editor should not crash. Ideally it should block or gracefully reject the invalid blend mode/Nanite combination, consistent with the warning it already logs.

### Observed Result

Editor crashes with an unhandled assertion.

### Affects Versions

5.8

### Platform(s)

Windows

### For crash reports, include your callstack

LogStaticMesh: Warning: Invalid material [NewMaterial] used on Nanite static mesh [SM\_Drone\_Two\_Mats].  
Only opaque or masked blend modes are currently supported, [BLEND\_TranslucentColoredTransmittance] blend mode was specified.

LogWindows: Error: appError called: Assertion failed: Nanite::IsSupportedBlendMode(ShadingMaterial)  
[File:D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\Lumen\LumenSceneCardCapture.cpp] [Line: 312]

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**Author:** ![Bug-Reporter](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/bug-reporter/32/997076_2.png) [@Bug-Reporter](https://forums.unrealengine.com/u/Bug-Reporter)\
**Post date:** [October 23, 2026, 3:01pm UTC](https://forums.unrealengine.com/t/editor-crash-unhandled-assert-when-changing-blend-mode-on-a-material-assigned-to-a-nanite-static-mesh/2764048/3 "2026-10-23T15:01:13Z")

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UE-405757 has been ‘Closed’ as a duplicate of an existing known issue. Origin Issue: UE-393900, Origin Topic: [Unreal Crashes 5.81](https://forums.unrealengine.com/t/unreal-crashes-5-81/2746230)