Ajuda para desvendar um Erro - HTTP 500

HTTP Status 500 - 

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type Exception report

message 

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

org.apache.jasper.JasperException: getOutputStream() has already been called for this response
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:387)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


root cause 

java.lang.IllegalStateException: getOutputStream() has already been called for this response
	org.apache.catalina.connector.Response.getWriter(Response.java:599)
	org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:195)
	org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:124)
	org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:117)
	org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:191)
	org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:115)
	org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
	org.apache.jsp.GeraRelatorio_jsp._jspService(GeraRelatorio_jsp.java:132)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:332)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


note The full stack trace of the root cause is available in the Apache Tomcat/5.5.17 logs.