Class "UInstancedStaticMeshComponent" deliberately leaves null pointers in the "InstanceBodies" array of FBodyInstances. This can be seen in methods such as:


However, method UInstancedStaticMeshComponent::RemoveInstanceInternal() does not take this into account, and the following code crashes the engine by attempting to access such null pointers:

// Re-target instance indices for shifting of array.
for (int32 i = InstanceIndex; i < InstanceBodies.Num(); ++i)
InstanceBodies[i]->InstanceBodyIndex = i;

[Link Removed]

Vitor Barata 2023-10-19 03:32:14 UTC
Hi [~W014KNNASUF], I've got a JIRA report related to case 00633572.

Steps to Reproduce
  • Open the engine and create a new level
  • Create a blueprint and add a InstancedStaticMeshComponent to it. Set it up with any static mesh.
  • In the ConstructionScript, EventBeginPlay, or any other event you can call in the Editor:
  • Add a 1st instance with the default transform
  • Add a 2nd instance with scale (0,0,0)
  • Remove instance at index 0
  • When running this code, the engine will crash on the removal

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ComponentUE - Rendering Architecture
Affects Versions5.3
Target Fix5.4
Fix Commit29084185
Main Commit29084194
CreatedOct 19, 2023
ResolvedOct 25, 2023
UpdatedNov 16, 2023
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