5.6 Regression: PCG Crashing when using Attribute Remove Duplicates on a string custom attribute

Development Programming & Scripting
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1

Hello,

I updated from Unreal 5.5.4 to Unreal 5.6.0 and noticed that my PCG graph is now crashing.
After some investigation, I noticed that it crashes when I use the Attribute Remove Duplicates node on a custom attribute of type string.

This is a regression since it is working perfectly fine on 5.5.4.

The PCG Graph looks like this:

image
image2183×455 90.3 KB

When generating, the engine (and editor) crashes with the following call stack:

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 1067]
Array index out of bounds: 0 into an array of size 0

UnrealEditor_Core
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_PCG
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll

You can find a sample project that replicate the issue here:

I will also file a separate report directly through the support but I wanted to share it on the forum so others can share and be updated when it is solved.

2

Hey! I came across the same issue recently.
I made a bug report just in case.
But meanwhile for my specific use case I found a good workaround of first hashing the strings and then using the remove duplicate attributes node.

Hope this helps!

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image504×239 22.8 KB

3

We ended up “rewriting” this node ourselves but I’ll try it out soon as this is way less annoying :smiley:
Thanks for the tip !