libs.CopyLibs.classpath=C\:/Program Files/NetBeans 8.0/java/ant/extra/org-netbeans-modules-java-j2seproject-copylibstask.jar set this in yor netbeans go to netbeans tools>options> java tab and add properties libs.CopyLibs.classpath=C\:/Program Files/NetBeans 8.0/java/ant/extra/org-netbeans-modules-java-j2seproject-copylibstask.jar