Why is AJAX returning HTTP status code 0?

Question

For some reason, while using AJAX (with my dashcode developed application) the browser just stops uploading and returns status codes of 0. Why does this happen?

Answer 1

Status code 0 means the requested url is not reachable. By changing http://something/something to https://something/something worked for me. IE throwns an error saying "permission denied" when the status code is 0, other browsers dont.