Steps to Reproduce

1. run the code

    <image id="img" />
<dropupload detection="none"  onUpload='img.setContent(event.media)'>
</dropupload>

2. drop any image on it

Current Result

2018-06-14 17:22:04 [ERROR] AuUploader:245 - Failed to upload
java.lang.NullPointerException
at org.zkoss.xml.XMLs.encodeText(XMLs.java:83)
at org.zkoss.zk.au.http.AuUploader.escapeParam(AuUploader.java:477)
at org.zkoss.zk.au.http.AuUploader.service(AuUploader.java:144)
at org.zkoss.zk.au.http.DHtmlUpdateServlet.doGet(DHtmlUpdateServlet.java:455)
at org.zkoss.zk.au.http.DHtmlUpdateServlet.doPost(DHtmlUpdateServlet.java:495)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)

Expected Result

no error