Error 8031

Invalid variation relationship: The same SKU is
specified as both a variation child and a variation parent. Please
resubmit with different SKU's for variation child and variation
parent relationships.

This error code only applies to variation relationships. It is returned when a new relationship causes a SKU to be both a variation child and a variation parent. For example, if an existing relationship existed where SKU1 was the parent of SKU2, then this error would be triggered by sending in a relationship where SKU1 is a child or where SKU2 is a parent.

To eliminate a relationship, you can delete either the parent or child product. When you delete a parent, you remove the relationship between that parent and all its children. When you delete a child product, you eliminate the relationship between just that one child product and its parent.

After you remove the original relationship, you can re-assign the child product to a new parent product.

See Creating Product Relationships.