Alternating 503 Errors and 201 Success When Uploading Images

[yoshi-pi]

When uploading an image as shown below, a 503 Service Unavailable error is returned. However, if the browser is reloaded and the image is uploaded again, a 201 Created response is returned. Reloading the browser again results in a 503 Service Unavailable error. This pattern repeats. Why is this happening? I'd like it to always return 201.

html

<input type="file"/>

javascript

let input = document.querySelector('input');
input.addEventListener('change', () => {
  let file = input.files[0];
  fetch('https://jsonplaceholder.typicode.com/posts', {
    method: 'POST',
    body: file,
  });
});