mi formulario html se ve así

 <form id="upload-form" class="dropzone"> <!-- this is were the previews should be shown. --> <div class="previews"></div> <!-- Now setup your input fields --> <input type="file" name="file"> <button type="submit">Submit data and files!</button> </form>

y la configuración del script

 Dropzone.options.uploadForm = { // The camelized version of the ID of the form element // The configuration we've talked about above autoProcessQueue: false, uploadMultiple: true, parallelUploads: 100, maxFiles: 100, // The setting up of the dropzone init: function() { var myDropzone = this; // First change the button to actually tell Dropzone to process the queue. this.element.querySelector("button[type=submit]").addEventListener("click", function(e) { // Make sure that the form isn't actually being sent. e.preventDefault(); e.stopPropagation(); myDropzone.processQueue(); }); // Listen to the sendingmultiple event. In this case, it's the sendingmultiple event instead // of the sending event because uploadMultiple is set to true. this.on("sendingmultiple", function() { // Gets triggered when the form is actually being sent. // Hide the success button or the complete form. }); this.on("successmultiple", function(files, response) { // Gets triggered when the files have successfully been sent. // Redirect user or notify of success. }); this.on("errormultiple", function(files, response) { // Gets triggered when there was an error sending the files. // Maybe show form again, and notify user of error }); } }

Busco mucho en Internet y, mientras leo el documento y otros ejemplos, debería funcionar, pero no es así.