Why does uploading image to imgur get 401 error code?

Question

This is my code in frontend but I when I perform upload2Imgur function, the result I receive is: { "data": { "error": "Authentication required", "request": "/3/image", "method": "GET" }, "success": false, "status": 401 } My Code for getting accessToken and function to upload: ` let accessToken = null;

  const getAccessToken = async () => {
    const response = await fetch('/imgur');
    const data = await response.json();
    return data.accessToken;
  }

  const upload2Imgur = async (files) => {
    const links = []
    if (!accessToken) {
      accessToken = await getAccessToken();
    }
    console.log(accessToken)
    console.log(files);
    for (let i = 0; i < files.length; i++) {
      let formData = new FormData()
      formData.append('image', files[i])
      let headers = new Headers()
      headers.append('Authorization', 'Bearer ' + accessToken)
      const response = await fetch('https://api.imgur.com/3/image', {
        headers: headers,
        method: 'POST',
        body: formData,
        redirect: 'follow'
      });
       const data = await response.json()
      links.push(data.data.link);
    }
    return links;
  }`

Please help me figure out what is wrong with my code. Thank you!