'Unrecognized Slot name' error on v-slot:header declaration

Vue JS: Draggable div error_ draggable element must have an item slot First, you need implement the component, i choose a component that delegates movement of container on header, you can move function 'drag error_ draggable element must have an item slot 1、Error: draggable element must have an item slot 升级组件npm i -S vuedraggable@next 使用示例div class=col-3> h3>Draggable 1h3> d

error slot slot content may have changed force update slots and mark instance for ` + `Note the target element must exist before the component is mounted