Vertex paint crashes editor

Development Platform & Builds
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1

When I try to paint vertex colors onto my meshes, the editor throws an exeption in the ColorVertexBuffer.cpp, Line 313:

if( VertexData != NULL && NumVertices > 0 )

It tells me the following:
Read access violation error
“this” was “0xFFFFFFFFFFFFFFC7”.

2

I found out that the editor only crashes when I paint the vertices and do anything else afterwards without saving. So when I switch to another mesh for painting by clicking on it, switch from vertex paint mode to object mode, enable a buffer visualization, etc. the editor crashes.

However if I paint one mesh, next go right to File->Save current and THEN do something else (e.g. switch to the next mesh), the editor doesn’t crash. But this can’t be it, right? Do I really need to save after every step to prevent the editor from crashing?

3

I switched my graphics card with a newer model to see if maybe the gpu was too old for UE4. Nothing changed and the editor still keeps crashing.

4

So I was able to reproduce the crash:

  1. Start the UE 4.17 source build
  2. Download and start the “Landscape Mountains” sample project
  3. Drag two pine tree meshes onto the map (NO instance paint on landscape!)
  4. Go to vertex paint mode and paint on one tree
  5. Still in vertex painting mode, click on the other tree
  6. Crash

I have a feeling that it has something to with the lod’s, because when I do the same thing to simple starter content meshes (with no lod’s), the vertex painting works just fine.

5

Can anyone confirm that behaviour? And if so, can anyone at Epic tell me if they know about it, please?