Ajax - JSON doesnt get sent in PATCH only

First, check that you use latest version of jQuery library:

• Older versions directly restrict unknown methods (PATCH is new one).
• I've tested on jQuery 1.7 - PATCH method working without problems.

Second, not all browsers supports PATCH method using XMLHttpRequest:

• Like, IE 7,8 (9+ works okay) have XMLHttpRequest, but it throws an error on PATCH:

  new XMLHttpRequest().open('PATCH', '/'); //Illegal argument
  

• To fix this, you may force jQuery to use the old proprietary ActiveXObject xhr, like so:

  $.ajax({
      url : 'http://127.0.0.1:8001/api/v1/pulse/7/',
      data : data,
      type : 'PATCH',
      contentType : 'application/json',
      xhr: function() {
          return window.XMLHttpRequest == null || new window.XMLHttpRequest().addEventListener == null 
              ? new window.ActiveXObject("Microsoft.XMLHTTP")
              : $.ajaxSettings.xhr();
      }
  });          
  

A bit late, but this worked for me when I got this error:

$.ajax({
  url : 'http://127.0.0.1:8001/api/v1/pulse/7/',
  data : JSON.stringify(data),
  type : 'PATCH',
  contentType : 'application/json',
  processData: false,
  dataType: 'json'
});

Serializing the object yourself instead of letting jQuery do it seems to help. This works for me on the latest version of Chrome, but still doesn't fix the ie problems mentioned in other responses.