Why does the mesh turn magenta in Weight Paint? For me the mesh is blue and of course turns red and green when painted. (Using Blender 4.3.1)
Hello Hawkline,
Great question. Magenta means that there is no vertex group that matches the bone name you have selected.
You will only see this when you have both the mesh and the armature selected. (and you're in weight paint mode on the mesh obviously)
By Default the Blue colour can mean 2 things.
Either a weight of zero OR the vertex is not part of the group.
You can change the way Blender displays zero weights so they show up as Black. (leaving Blue to mean 0)
I would recommend this because it can help you see an issues.
Hope that helps.
TL;DR
Magenta means missing in Blender