By repeating the same query you get this error on liberoquotidiano.it (it's not a Denial of Service). org.apache.jasper.JasperException: org.apache.jasper.JasperException: org.apache.jasper.JasperException: java.lang.NullPointerException at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:549) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:455) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at CharsetFilter.doFilter(CharsetFilter.java:78) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:2...