1. options has an unknown property 'overlay'

client: {
    overlay: {
      
    }
}

2. webpack < 5 used to include polyfills for node.js core modules by default.

This is no longer the case. Verify if you need this module and configure a polyfill for it.
If you want to include a polyfill, you need to:

• add a fallback 'resolve.fallback: { "path": require.resolve("path-browserify") }'
• install 'path-browserify'
  If you don't want to include a polyfill, you can use an empty module like this:
  resolve.fallback: { "path": false }
  按照报错提示在代码中添加相应配置即可: 先安装依赖npm install path-browserify

configuareWebpack: {
    resolve: {
        alias: {
        },
        fallback:{
            path: require.resolve("path-browserify")
        }
    }
}

3.ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.

• options has an unknown property 'after'. These properties are valid:
  object { allowedHosts?, bonjour?, client?, compress?, devMiddleware?, headers?, historyApiFallback?, host?, hot?, http2?, https?, ipc?, liveReload?, magicHtml?, onAfterSetupMiddleware?, onBeforeSetupMiddleware?, onListening?, open?, port?, proxy?, server?, setupExitSignals?, setupMiddlewares?, static?, watchFiles?, webSocketServer? }

经查阅官方文档webpack5-devServer,after和before已弃用，分别用middlewares.push和middlewares.unshift替代

devServer: {
    setupMiddlewares: (middlewares, devServer) => {
      if (!devServer) {
        throw new Error('webpack-dev-server is not defined');
      }

      devServer.app.get('/setup-middleware/some/path', (_, response) => {
        response.send('setup-middlewares option GET');
      });
    }
}

4. devServer获取post传递参数undefined

以前的写法

// 安装 body-parser
npm install body-parser
const bodyParser = require(‘body-parser’);
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: true
}));

express 4.X版本不需要额外加载body-parser

const express = require(‘express’);
devServer.app.use(express.json());
devServer.app.use(express.urlencoded({
    extended: true
}));