500 Servlet Exception

java.lang.IllegalStateException: sendError() forbidden after buffer has
been committed.
	at com.caucho.server.connection.AbstractHttpResponse.sendError(AbstractHttpResponse.java:452)
	at com.caucho.server.connection.AbstractHttpResponse.sendError(AbstractHttpResponse.java:439)
	at com.caucho.server.dispatch.ErrorFilterChain.doFilter(ErrorFilterChain.java:69)
	at com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:115)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
	at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:277)
	at com.caucho.server.webapp.RequestDispatcherImpl.error(RequestDispatcherImpl.java:113)
	at com.caucho.server.webapp.ErrorPageManager.sendServletError(ErrorPageManager.java:363)
	at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:180)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
	at com.caucho.server.hmux.HmuxRequest.handleRequest(HmuxRequest.java:419)
	at com.caucho.server.port.TcpConnection.run(TcpConnection.java:389)
	at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:507)
	at com.caucho.util.ThreadPool.run(ThreadPool.java:433)
	at java.lang.Thread.run(Unknown Source)