AJAX Request CORS Policy error with Flask

You can use this to test that it's actually a CORS issue. This worked for me.

@app.after_requestdef after_request(response):    header = response.headers    header['Access-Control-Allow-Origin'] = '*'    header['Access-Control-Allow-Headers'] = 'Content-Type, Authorization'    header['Access-Control-Allow-Methods'] = 'OPTIONS, HEAD, GET, POST, DELETE, PUT'    return response

The header Access-Control-Allow-Origin must be returned from Flask, not requested by AJAX. So it would be something like this:

def get_content():    return "It works!", 200@app.route('/')def home():    content, status_code = get_content()    headers = {'Access-Control-Allow-Origin': '*'}    return content, status_code, headers

Thank you all for the help. I already solved the problem. I was making requests to HTTP PTZ Camera which don't let me make requests from client side (I've no idea why). So I hack the problem, and now I'm making requests to my server, and my server make the request to the camera. Here you've what I'm doing:

$.ajax({url: 'http://127.0.0.1:5000/teste00',        type: "GET",        success: function (result) {},        });

On server side:

@system.route('/teste00')def teste():    response = requests.get('camera_url')   return response.content