<form name="add_avatar" enctype="multipart/form-data">
            <input type="file" name="avatar" accept="image/*">
            <input type="text" value="5" name="code" readonly style="display: none;">
</form>

        "Отправить": function() {
            var theForm = $(document.forms['add_avatar']).serialize()
            $.ajax({
              type: 'GET',
              url: 'usl',
              data: theForm,
              success: function(data) {
                  var obj = jQuery.parseJSON( data )
                  if (obj.code == 1){
                      setTimeout("window.location.href = 'url'", 300);
                  } else {
                      $('.validateTips').html(obj.request)
                  }
              },
              error:  function(xhr, str){
                $('.validateTips').html('Возникла ошибка: ' + xhr.responseCode);
                }
            });

MultiValueDictKeyError at url
"'avatar'"