前言

在做新的需求需要变更vue的项目代码时突然出现报错

TypeError: Cannot read property ‘headers’ of null at Server.socket.on (***/node_modules/webpack-dev-server/lib/servers/SockJSServer.js:68:32)

不清楚为什么突然出现了这个问题，之前在这个vue项目进行改动也是正常的，那么也说一下我的解决方法

解决步骤

问题复现

首先是package.json情况:

{
  "name": "manufacturing-vue",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build && cd dist/prod && jar -cvf manufacturing-vue.war *",
    "test": "vue-cli-service build --mode test && cd dist/test && jar -cvf manufacturing-vue.war *",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "@ui5/webcomponents": "^1.0.0-rc.5",
    "axios": "^0.19.2",
    "core-js": "^2.6.5",
    "element-ui": "^2.12.0",
    "js-cookie": "^2.2.1",
    "pixi.js": "^5.3.7",
    "three": "^0.123.0",
    "three-js": "^79.0.0",
    "vue": "^2.6.10",
    "vue-router": "^3.0.3",
    "vuex": "^3.0.1",
    "xlsx": "^0.15.6"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "^3.11.0",
    "@vue/cli-plugin-eslint": "^3.11.0",
    "@vue/cli-service": "^3.11.0",
    "babel-eslint": "^10.0.1",
    "element-theme-chalk": "^2.12.0",
    "eslint": "^5.16.0",
    "eslint-plugin-vue": "^5.0.0",
    "gulp": "^4.0.2",
    "node-sass": "^4.14.1",
    "sass-loader": "^8.0.0",
    "uglify-es": "^3.3.9",
    "vue-template-compiler": "^2.6.10"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
    "rules": {
      "no-console": "off"
    },
    "parserOptions": {
      "parser": "babel-eslint"
    }
  },
  "prettier": {
    "printWidth": 160
  },
  "postcss": {
    "plugins": {
      "autoprefixer": {}
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions"
  ]
}

此时使用npm run serve运行程序:
报错信息如下:

xxx\node_modules\webpack-dev-server\lib\servers\SockJSServer.js:67
      f(connection, connection.headers);
                               ^

TypeError: Cannot read property 'headers' of null
    at Server.<anonymous> (xxx\node_modules\webpack-dev-server\lib\servers\SockJSServer.js:67:32)
    at Server.emit (events.js:400:28)
    at App.emit (xxx\node_modules\sockjs\lib\sockjs.js:196:29)
    at xxx\node_modules\sockjs\lib\transport.js:111:25
    at processTicksAndRejections (internal/process/task_queues.js:77:11)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! manufacturing-vue@0.1.0 serve: `vue-cli-service serve`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the manufacturing-vue@0.1.0 serve script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     xxx\npm-cache\_logs\2023-06-27T01_38_41_040Z-debug.log

分析

这是一个TypeError类型的错误，报错位置在SockJSServer.js中第67行，具体错误信息是“Cannot read property ‘headers’ of null”，意思是null对象无法读取属性’headers’，因为null并没有该属性。错误是在尝试使用连接的headers属性时发生的。可能的原因是connection对象为null或未定义。

查找百度:

点击查看报错分析

在这里插入图片描述

发现它已经是被修复状态

点击内部的git链接,修复的信息为:

报错修复提交信息

同时查找它的修复问题的版本为3.8.1

意味着需要安装版本大于3.8.1的webpack-dev-server就可以解决修复该问题

问题解决

使用安装命令

npm install webpack-dev-server@3.9.0

理论上，只需要安装的webpack-dev-server的版本大于3.8.1，就可以解决这个报错

此时，package.json的安装情况:

{
  "name": "manufacturing-vue",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build && cd dist/prod && jar -cvf manufacturing-vue.war *",
    "test": "vue-cli-service build --mode test && cd dist/test && jar -cvf manufacturing-vue.war *",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "@ui5/webcomponents": "^1.0.0-rc.5",
    "axios": "^0.19.2",
    "core-js": "^2.6.5",
    "element-ui": "^2.12.0",
    "js-cookie": "^2.2.1",
    "pixi.js": "^5.3.7",
    "three": "^0.123.0",
    "three-js": "^79.0.0",
    "vue": "^2.6.10",
    "vue-router": "^3.0.3",
    "vuex": "^3.0.1",
    "xlsx": "^0.15.6"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "^3.11.0",
    "@vue/cli-plugin-eslint": "^3.11.0",
    "@vue/cli-service": "^3.11.0",
    "babel-eslint": "^10.0.1",
    "element-theme-chalk": "^2.12.0",
    "eslint": "^5.16.0",
    "eslint-plugin-vue": "^5.0.0",
    "gulp": "^4.0.2",
    "node-sass": "^4.14.1",
    "sass-loader": "^8.0.0",
    "uglify-es": "^3.3.9",
    "vue-template-compiler": "^2.6.10",
    "webpack-dev-server": "3.9.0"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
    "rules": {
      "no-console": "off"
    },
    "parserOptions": {
      "parser": "babel-eslint"
    }
  },
  "prettier": {
    "printWidth": 160
  },
  "postcss": {
    "plugins": {
      "autoprefixer": {}
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions"
  ]
}