代理错误：无法将请求/ api / stores从http：// localhost：3000代理到http：// localhost：5000

Question

我正在DigitalOcean上运行我的MERN应用程序，并且似乎收到代理错误，以响应来自对本地主机上的Express服务器的请求。但是这个问题在Heroku上并没有持续存在。 （代理错误：无法将请求/ api / stores从http://localhost:3000代理到http://localhost:5000）。我应该怎么做才能解决这个问题？

我的客户端程序包json是：

{
  "name": "client",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "cryptr": "^4.0.2",
    "jquery": "^3.4.1",
    "jquery.soap": "^1.7.3",
    "react": "^16.8.6",
    "react-dom": "^16.8.6",
    "react-router-dom": "^5.0.1",
    "react-scripts": "3.0.1",
    "xhr2": "^0.2.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "proxy": "http://localhost:5000"
}