If you get this error when you try to upload a file  and you already have added the extension to setAllowedExtentions. Extension is not allowed (valid: , ace, arc, arj, asf, au, avi, bmp, bz2, cab, cda, css, csv, dmg, doc, docx, dotm, dotx, flv, gif, gpx, gz, hqx, ico, jar, jpeg, jpg, js, kml,