Operating system: Windows 10
Graphics card: GTX 970
example: 2.79b release
There is a problem with the way the Blender handles newly created vertex groups that causes numerous problems.
- Tools > Weight Tools - These tools do not work on newly created vertex groups.
- The Fix Deforms tool immediately crashes blender.
- Bmesh cannot access vertex groups layer and returns: AttributeError: BMElem[key]: invalid key, must be a BMLayerItem
- Open new Blend
- Create Cube
- Add Vertex Group
- Enter Weight Paint Mode
- Press V to enter Vertex Mask mode
- If required, press A to select all vertices
- Press Tools > Weight Tools > Invert
- Nothing happens
- Press Fix Deforms
- Blender crashes
Using the weight paint brush in an empty space, or manually assigning a vertex to the vertex group in the properties window will allow the weight tools to work as expected. However this is not an acceptable workaround when using Bmesh to manager vertex groups.