getOutputStream() has already been called for this response error

exception

org.apache.jasper.JasperException: java.lang.IllegalStateException: getOutputStream() has already been called for this response org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:584) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:466) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

root cause

java.lang.IllegalStateException: getOutputStream() has already been called for this response org.apache.catalina.connector.Response.getWriter(Response.java:627) org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:215) javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:105) org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118) org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:190) org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:123) org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:80) org.apache.jsp.DownloadResume_jsp._jspService(DownloadResume_jsp.java:91) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)