I have this script defined for a google sheet in Apps Script:

function doPost(e) {
  var app = SpreadsheetApp.getActive();
  var sheet = app.getSheetByName('Web');

  var content = JSON.parse(e.postData.contents)
  sheet.getRange("A1").setValue(content);

  return ContentService.createTextOutput("Saved");
}

I Implemented it as Web Application and set the access to Anyone.

Then tried sending post request through postman to the generated url and it worked flawlesly. Also tried other postman like apps. Everything without issues. The content body of the request is always stored in the "A1" cell.

But when I want to send exactly the same request using Fetch API from my Vue.js web app. It fails with error: TypeError: Failed to fetch. Nothing else can be read from the error. No status code, nothing. Body of the function that is called on button click from my web app:

function sendForm() {

    var myHeaders = new Headers();
    myHeaders.append("Content-Type", "application/json");

    var raw = JSON.stringify({
        "test": "testing from vue"
    });

    var requestOptions = {
        method: 'POST',
        headers: myHeaders,
        body: raw,
        redirect: 'follow'
    };

    fetch("https://script.google.com/macros/s/<id of the implementation>/exec", requestOptions)
        .then(response => response.text())
        .then(result => console.log(result))
        .catch(error => console.log('error', error));
}

The javascript code was generated from the postman itself, so there should be no differences.

This is the console output:

Also tried axios. Similar issue, but the error was different: Network Error.

I have no idea what to do or where to look. I googled for several hours but nothing I found helped. If anyone have an idea what could be the reason, I would be super grateful.