Upload component will not start upload

I am given this error when trying to upload an image. I was hoping someone else has gotten this error and knows a solution. I am using the current vaadin 8. I have added Listeners to see if the Upload has started or failed and neither actually run. I have blacked out part of the image for privacy concerns.

I did a really quick and dirty test, which seems to work:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
    Upload upload = new Upload("Upload THIS", new Upload.Receiver() {

        public OutputStream receiveUpload(String s, String s1) {
            try {
            } catch (IOException e) {
            return baos;
    Button button = new Button("Print uploaded file");
    button.addClickListener(event -> {
        Notification.show(new String(baos.toByteArray()));