Unreal Engine Assertion Failed: IsRotationNormalized() Error

I always get this error when I test the game. I just made the project with blueprint

Assertion failed: IsRotationNormalized() [File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Math\TransformVectorized.h] [Line: 1300]

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I have the same error when i duplicate a blueprint class inheriting from a custom C++ Actor in the 5.1

I fixed this error by creating a valid FQuat instead of a default one.

My code was looking like this:

DisplayMeshCmp->SetRelativeTransform(FTransform(FQuat(), FVector(0, 0, 0)));

This was ok in a BluePrint class based on the C++ class, but as soon I was creating a child of this Blueprint, the editor crashed consistantly at each duplicate.

By creating a valid FQuat using the static call FQuat::Identity, the issue is gone.

DisplayMeshCmp->SetRelativeTransform(FTransform(FQuat::Identity, FVector(0, 0, 0)));

The error message of Unreal is clear in a way, that’s at least what’s point me to this specific call.

My suggestion to prevent this is: never use a call to the empty constructor of FQuat, and by extension, FVector, FRotator and FTransform, even if you modify them right after.

All the best.