出现这个问题，那么很有可能还是按照vue2的方式使用的Vue Router，建议先去了解下Vue Router 3。

解决问题示例代码如下：

//router.js
import * as vueRouter from "vue-router";
import Home from "../views/Home.vue";

const routes = [
  {
    path: "/index",
    name: "Home",
    component: Home
  }
];

const router = vueRouter.createRouter({
  history: vueRouter.createWebHistory(),
  routes: routes
});
export default router;

或者：

//router.js
import {createRouter,createWebHistory} from "vue-router";
import Home from "../views/Home.vue";

const routes = [
  {
    path: "/index",
    name: "Home",
    component: Home
  }
];

const router = createRouter({
  history: createWebHistory(),
  routes: routes
});
export default router;

//main.js
import { createApp } from 'vue'
import App from './App.vue'
import router from './router'
createApp(App).use(router).mount('#app')

如上，vue3跟vue2的区别还是蛮大的，所以使用之前建议还是先去了解下vue3与vue2的区别。