How to add header data in XMLHttpRequest when using formdata?
Your error InvalidStateError: An attempt was made to use an object that is not, or is no longer, usable appears because you must call setRequestHeader after calling open. Simply move your setRequestHeader line below your open line (but before send): xmlhttp.open(“POST”, url); xmlhttp.setRequestHeader(“x-filename”, photoId); xmlhttp.send(formData);