Symmetrize Bones / Mirror Bones I'm selecting necessary bones, go to the Names &gt; AutoName Left/Right, and when I press Symmetrize it turns out like illustrated in the picture.


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Because you're expecting the symmetry to happen on the Y axis but the Symmetrize operation uses the X axis, so you need to rotate your armature 90° on the Z axis in Edit mode and symmetrize again. What we see is what is supposed to happen, your bones have been mirrored on the X axis.