Access to XMLHttpRequest from origin 'http://localhost:3000' has been blocked by CORS policy

I am a new bee to React. I am creating a small CRUD application. I have a listing of all users. for that, I have an API which is working fine on postman but giving issue when I use that API in my react app. Here is the error that I am getting

Access to XMLHttpRequest at '' from origin 'http://localhost:3000' has been blocked by CORS policy: Request header field access-control-allow-origin is not allowed by Access-Control-Allow-Headers in preflight response.

But if i change the Url from to, then works fine.

Here is my code.

constructor(props) {
    this.state = {
      items: [],
      isLoaded: false

  componentDidMount() {
    // const token = 'pt7_VZpxd6jOooNILFwO1qEc5lzLifeN';
    let webApiUrl = '';
    // let webApiUrl = '';

    axios.get(webApiUrl, {
      method: "GET",
      mode: "no-cors",
      headers: {
        "Content-Type": "application/json",
        // "Authorization": "Bearer " + token,
        "Access-Control-Allow-Methods": "GET",
        "Access-Control-Allow-Origin": "*",
    .then( res => {
      this.setState({ isLoaded: true, items:})

I have followed these link No 'Access-Control-Allow-Origin' header is present on the requested resource—when trying to get data from a REST API , Access to XMLHttpRequest has been bloked by CORS policy But still stuck with the issue. How to solve this issue. Any help would be appreciated.

1 answer

  • answered 2020-11-25 08:15 lala

    If you use your own backend then, it would be much more easier and focus if you add "proxy": "http://localhost:3000" or whatever your backend host port you have specified in your client or react project folder, like so:-

    • client/package.json or reactFolder/package.json
      "name": "projectname",
      "version": "0.1.0",
      "private": true,
      "dependencies": {
      "proxy": "http://localhost:5000"

    Then you can just do:-

    await axios.get('/api/products') // straight away use whatever path you've specified