"found multiple roots" even thought I have only 1

Do you mean joint17, join1, joint5 are on the same level as joint9 couse for me it looks like they are on the same level as joint10. And then what makes it working when I remove the arm, joint1, and leg, joint16 even if they would be on same level?

E: Tried to make 1 more root bone Screenshot by Lightshot still same, “multiple root bones found” wtf??