I met this error when usling 1.9 version, My JDK is 1.6, seems you use JDK

Directory MultiFileUpload
1

I met this error when usling 1.9 version, My JDK is 1.6, seems you use JDK1.7 to compile?
java.lang.UnsupportedClassVersionError: com/wcs/wcslib/vaadin/widget/multifileupload/ui/UploadFinishedHandler : Unsupported major.minor version 51.0