# UnrealEditor-CoreUObject.dll!UnknownFunction --\> Error when packaging 

**URL:** <https://forums.unrealengine.com/t/unrealeditor-coreuobject-dll-unknownfunction-error-when-packaging/1677072>\
**Category:** Programming & Scripting\
**Tags:** unreal-engine, question, Blueprint\
**Created:** [February 9, 2024, 8:09pm UTC](https://forums.unrealengine.com/t/unrealeditor-coreuobject-dll-unknownfunction-error-when-packaging/1677072 "2024-02-09T20:09:11Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![imagineer](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/imagineer/32/562003_2.png) [@imagineer](https://forums.unrealengine.com/u/imagineer)\
**Post date:** [April 29, 2024, 6:38pm UTC](https://forums.unrealengine.com/t/unrealeditor-coreuobject-dll-unknownfunction-error-when-packaging/1677072/2 "2024-04-29T18:38:35Z")

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> [@how should I fix this packaging error?](https://forums.unrealengine.com/t/how-should-i-fix-this-packaging-error/1189670):
>
> hey everyone. please help me to fix this error. I got this kind of error repeating in my Output log when I tried to package my game in ue5.1 and I don’t even know where to look for the problem! PackagingResults: Error: begin: stack for UAT PackagingResults: Error: === Handled ensure: === PackagingResults: Error: Ensure condition failed: ClassDefaultObject [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\BlueprintGeneratedClass.cpp] [Line: 1635] PackagingResults: Error: Stack: …

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