Help Required:Pls explain y this exception has come?

Hi All,

Any idea y this exception is thrown

java.lang.NullPointerException

at org.jivesoftware.openfire.spi.RoutingTableImpl.routePacket(RoutingTableImpl.jav a:236)

at org.jivesoftware.openfire.net.SocketPacketWriteHandler.process(SocketPacketWrit eHandler.java:53)

at org.jivesoftware.openfire.spi.PacketDelivererImpl.deliver(PacketDelivererImpl.j ava:48)

at org.jivesoftware.openfire.handler.IQHandler.process(IQHandler.java:51)

at org.jivesoftware.openfire.IQRouter.handle(IQRouter.java:351)

at org.jivesoftware.openfire.IQRouter.route(IQRouter.java:101)

at org.jivesoftware.openfire.spi.PacketRouterImpl.route(PacketRouterImpl.java:68)

at org.jivesoftware.openfire.SessionPacketRouter.route(SessionPacketRouter.java:10 0)

at org.jivesoftware.openfire.SessionPacketRouter.route(SessionPacketRouter.java:61 )

at org.jivesoftware.openfire.http.HttpSession.sendPendingPackets(HttpSession.java: 611)

at org.jivesoftware.openfire.http.HttpSessionManager$HttpPacketSender.run(HttpSess ionManager.java:373)

at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java: 886)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)

at java.lang.Thread.run(Thread.java:662)

Thanks in advanceā€¦