# UEFN 43.00 fails to launch because Windows Smart App Control blocks its bundled dxcompiler.dll, causing ShaderCompileWorker to crash even after file verification. 

**URL:** <https://forums.unrealengine.com/t/uefn-43-00-fails-to-launch-because-windows-smart-app-control-blocks-its-bundled-dxcompiler-dll-causing-shadercompileworker-to-crash-even-after-file-verification/2851047>\
**Category:** Issues and Bug Reporting\
**Tags:** unreal-engine, question\
**Created:** [November 5, 2026, 5:58pm UTC](https://forums.unrealengine.com/t/uefn-43-00-fails-to-launch-because-windows-smart-app-control-blocks-its-bundled-dxcompiler-dll-causing-shadercompileworker-to-crash-even-after-file-verification/2851047 "2026-11-05T17:58:31Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Jimbohalo10](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/jimbohalo10/32/961440_2.png) [@Jimbohalo10](https://forums.unrealengine.com/u/Jimbohalo10)\
**Post date:** [November 5, 2026, 8:35pm UTC](https://forums.unrealengine.com/t/uefn-43-00-fails-to-launch-because-windows-smart-app-control-blocks-its-bundled-dxcompiler-dll-causing-shadercompileworker-to-crash-even-after-file-verification/2851047/2 "2026-11-05T20:35:43Z")

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> [@leoel](#):
>
> error status 0xc0e90002

Hi @leoel

This was a problem long while ago and its parts of Windows Defender.

[UEFN/Fortnite flagged as Malware from Microsoft Defender - General / Issues and Bug Reporting - Epic Developer Community Forums](https://forums.unrealengine.com/t/urc-exe-and-urc-dll-get-flagged-as-malware-from-microsoft-defender/1802519/2)

This needed to be added to the Windows Defender exception list as in the past thread

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