blender · HeyBraza shows you
blender bone heat weighting failed
HeyBraza points at the mesh cleanup steps and the ctrl+p menu so automatic weights finally completes.
'bone heat weighting failed' means blender's weight solver choked on the mesh - doubled vertices, loose geometry, non-manifold faces or an unapplied scale. clean those and the same parenting command works.
short answer
the solver fails on messy geometry: apply scale, merge doubled vertices, and delete loose geometry, then re-parent with ctrl+p > 'with automatic weights'. also check the bones actually sit inside the mesh - bones outside the surface have nothing to weight to.
or do it yourself
- 1select the mesh, go to object mode and press ctrl + a > 'scale' - a non-1 scale alone can break the solver.
- 2in edit mode select all (a) and press m > 'merge by distance' to kill duplicate vertices.
- 3still in edit mode, use select > 'all by trait' > 'loose geometry' and delete anything it finds (x > vertices).
- 4check the bones actually sit inside the mesh - bones outside the surface can't find geometry to weight.
- 5back in object mode select the mesh, shift-select the armature, then press ctrl + p > 'with automatic weights'.
steps last checked
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downloadcommon questions
what if it still fails?
parent with 'empty groups' instead, then paint the weights yourself in weight paint mode - slower, but it always works.
why did my model become huge after parenting?
the armature had an unapplied scale. select it, ctrl + a > 'scale', clear the parent, and parent again.
what does bone heat weighting failed actually mean?
it means blender's automatic weighting solver couldn't work out which vertices belong to which bone. it isn't a bug in your rig - it's the mesh: an unapplied scale, duplicate vertices, loose geometry, or bones sitting outside the surface all make the solver give up.