Crash when opening a level

Development Programming & Scripting
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1

Hello, I have persistent crashes when trying to open a specific level or trying to delete said level. I can open the project fine, but whenever I try to open this specific level it crashes, which is weird since it worked fine the day before with no issues.

The level is a mostly an empty level, just a plane for ground, some lighting and fog, a level sequencer and camera. I was going to use to record some niagara assets I’ve made (but hadn’t implemented yet). I could redo the level, but this is not the first time I’ve lost a level to crashes, more like the fifth time. It would be nice to know if it can be fixed or avoided in the future.

This is what the crash reporter says:

Assertion failed: UniformBufferStruct [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Classes\Materials\MaterialParameterCollection.h] [Line: 172]

UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_ContentBrowserAssetDataSource
UnrealEditor_ContentBrowserAssetDataSource
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_ContentBrowser
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_ContentBrowser
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
user32
user32
UnrealEditor_ApplicationCore
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
kernel32
ntdll

Any help would be appreciated!

2

Hello there @SophieEdqvist!

Considering the error you are encountering, your build has a conflict with a MPC, most likely due a material inside being corrupt, or tied to a faulty reference.

Assertion failed: UniformBufferStruct
[File: MaterialParameterCollection.h] [Line: 172]

The first step to resolve the problem would be to pinpoint which element is causing the crash. Test by renaming your MPC in content browser. This will cause the engine to skip loading those assets, and allow to open your level again. After that, remove any references, or re-assign to a clean MPC.

If the issue persists after that, test a clean cache via deletion of Saved and Intermediate folders, then re-generate the project. If all else fails, I would suggest re-rolling to a previous build from the Saved/Backup folder.