36 content-type The site returns a 406 error (Accept header request not accepted). If I try once more, the page loads. Then, the real kicker is that after the page loads successfully, the XMLHttpRequest no longer succeeds. This is a guide and reference to the XMLHttpRequest object, a key component to know in Ajax programming. Here is a brief example of a Web page that uses XMLHttpRequest. Well get into the details and ways to work-around various things that can go wrong later.