500 Servlet Exception

java.lang.IllegalStateException: forward() not allowed after buffer has
committed.
	at com.caucho.server.http.QRequestDispatcher.forward(QRequestDispatcher.java:131)
	at com.caucho.server.http.QRequestDispatcher.forward(QRequestDispatcher.java:103)
	at com.caucho.server.http.FileServlet.service(FileServlet.java:302)
	at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
	at com.caucho.server.http.Invocation.service(Invocation.java:315)
	at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
	at com.caucho.server.http.QRequestDispatcher.forward(QRequestDispatcher.java:223)
	at com.caucho.jsp.QPageContext.handlePageException(QPageContext.java:648)
	at _ring_0index__jsp._jspService(_ring_0index__jsp.java:751)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
	at com.caucho.jsp.Page.subservice(Page.java:506)
	at com.caucho.server.http.FilterChainPage.doFilter(FilterChainPage.java:182)
	at com.caucho.server.http.Invocation.service(Invocation.java:315)
	at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
	at com.caucho.server.http.RunnerRequest.handleRequest(RunnerRequest.java:346)
	at com.caucho.server.http.RunnerRequest.handleConnection(RunnerRequest.java:274)
	at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
	at java.lang.Thread.run(Thread.java:534)