确保端口是打开的

var app = express();
app.set('port', (process.env.PORT || 5000));

诸如此类，最后你得到了这个

app.listen(app.get('port'), function() {
    console.log("Node app is running at localhost:" + app.get('port'))
});

在node js中仍然是一个新手，但这导致了更多的这种情况。

我已经解决了我的问题。这不是一个NPM错误，它与代理行为有关。

如果你不支持代理，

MAC
 1.  Goto System Preference (gears icon on your mac)
 2.  click your network
 3.  click advanced
 4.  click proxy
 5.  check excludes simple hostnames
 6.  add this line below (Bypass Proxy Settings...) "localhost, localhost:8080"

refer to the npm echo: "Project is running at http://localhost:8080/"

Windows
 1.  Goto your browser Proxy Settings (google it)
 2.  check Bypass local address
 3.  add this line below "localhost, localhost:8080"

检查包装。Json文件，并在此文件中找到您的脚本名称

检查包装。Json文件有“脚本”属性是否存在。如果不这样更新脚本属性

{
  "name": "csvjson",
  "version": "1.0.0",
  "description": "upload csv to json and insert it into MongoDB for a single colletion",
  "scripts": {
    "start": "node csvjson.js"
  },
  "dependencies": {
    "csvjson": "^4.3.4",
    "fs": "^0.0.1-security",
    "mongodb": "^2.2.31"
  },
  "devDependencies": {},
  "repository": {
    "type": "git",
    "url": "git+https://github.com/giturl.git"
  },
  "keywords": [
    "csv",
    "json",
    "mongodb",
    "nodejs",
    "collection",
    "import",
    "export"
  ],
  "author": "karthikeyan.a",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/homepage/issues"
  },
  "homepage": "https://github.com/homepage#readme"
}

现在不鼓励全局安装create-react-app。相反，通过执行以下命令卸载全局安装的create-react-app包:npm uninstall -g create-react-app(如果这个命令对你不起作用，你可能不得不手动删除包文件夹。一些用户报告说，他们不得不手动删除文件夹)

然后你可以运行npx create-react-app my-app来再次创建react app。

裁判:https://github.com/facebook/create-react-app/issues/8086

对于我的例子，我在“First”文件夹中创建了React项目，我在这个文件夹中运行项目，所以我看到了同样的错误。你应该进入项目，然后你应该运行(为我的例子“反应电影”)。如果你看我的屏幕，你可以很容易地发现。