jQuery.uploadで「Uncaught SyntaxError: Unexpected token <」というエラーが出たら ref: http://qiita.com/shu_0115/items/c5bf6d5741bb62687583

jquery.upload-1.0.2.js

    switch (type) {
      case 'xml':
        data = parseXml(data);
        break;
      case 'json':
        // 自動挿入タグ除去
        data = data.replace(/<pre style="word-wrap: break-word; white-space: pre-wrap;">/g, '')
        data = data.replace(/<pre>/g, '')
        data = data.replace(/<\/pre>/g, '')

        data = window.eval('(' + data + ')');
        break;
    }
    return data;