vue报错[Vue warn]: Unknown custom element: <router-Link>

vue浏览器报错，如下

vue.runtime.esm.js?2b0e:619 [Vue warn]: Unknown custom element: <router-Link> - did you register the component correctly? For recursive components, make sure to provide the "name" option.

found in

---> <App> at src/App.vue
<Root>

原因：

没有注册插件router

//注册插件
Vue.use(VueRouter)