Deformation weirdness

I have a human rig where the neck bone, left arm bones and left hand bone all rotate the vertices that is assigned the upper spine bone. I don’t know what is wrong. These vertices are not assigned to the said bones. The parenting is good. I’ve used this rig on other characters and not had trouble, so please help me.

If you’re using Vertex Groups and not Envelopes, it sounds like the upper spine vertices must be assigned to the said bones. This happens sometimes with Bone Heat Weighting, you have to keep going back and correcting excess weighting bleed unless you’ve got high bone density (hahaha!).

In Weight Paint mode, make sure the brush has Opacity set to ‘1.0’ and has ‘Soft’ toggled OFF, set the brush to Sub, then select each of the problem bones in turn and paint over the affected verts. By putting the armature in Pose Mode and setting it to X-Ray before going into Weight Paint, you can scale or drag the problem bones all over the place while in Weight Paint, to get any stray vertices to show up more obviously.

They’re not assigned, I’ve now checked about 8 times, in both edit mode and weight paint… I completely made the vertex groups from scratch because I don’t like bone heat weighting.

If you haven’t already, in Edit Mode, select a problem vertex, and in the Transform Properties panel, double-check the Vertex Deform Groups listing – it’ll show all bones that vertex is linked to (i.e., which Vertex Groups it’s in), regardless of weight. It (they) may be included in some VGs you don’t expect. This can happen when Weight Painting in particular.

Thanks! Turns out that they were in one of the finger bones.