It seems that my Windows IE11 and Edge browsers are regularly reporting this exception since we updated to Vaadin 7.7.7 (we run on Tomcat 8 with Java 8).
2017-02-15 13:52:17,286 ERROR (com.esignforms.open.vaadin.EsfVaadinUI) init().VaadinSession.ErrorHandler.error()
java.lang.NullPointerException
at com.vaadin.server.communication.ServerRpcHandler.parseServerRpcInvocation(ServerRpcHandler.java:571)
at com.vaadin.server.communication.ServerRpcHandler.parseInvocation(ServerRpcHandler.java:534)
at com.vaadin.server.communication.ServerRpcHandler.parseInvocations(ServerRpcHandler.java:500)
at com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:336)
at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:273)
at com.vaadin.server.communication.PushHandler$2.run(PushHandler.java:148)
at com.vaadin.server.communication.PushHandler.callWithUi(PushHandler.java:240)
at com.vaadin.server.communication.PushHandler.onMessage(PushHandler.java:494)
at com.vaadin.server.communication.PushAtmosphereHandler.onMessage(PushAtmosphereHandler.java:87)
at com.vaadin.server.communication.PushAtmosphereHandler.onRequest(PushAtmosphereHandler.java:77)
at org.atmosphere.cpr.AsynchronousProcessor.action(AsynchronousProcessor.java:199)
at org.atmosphere.cpr.AsynchronousProcessor.suspended(AsynchronousProcessor.java:107)
at org.atmosphere.container.Servlet30CometSupport.service(Servlet30CometSupport.java:66)
at org.atmosphere.cpr.AtmosphereFramework.doCometSupport(AtmosphereFramework.java:2075)
at org.atmosphere.websocket.DefaultWebSocketProcessor.dispatch(DefaultWebSocketProcessor.java:571)
at org.atmosphere.websocket.DefaultWebSocketProcessor$3.run(DefaultWebSocketProcessor.java:333)
at org.atmosphere.util.VoidExecutorService.execute(VoidExecutorService.java:101)
at org.atmosphere.websocket.DefaultWebSocketProcessor.dispatch(DefaultWebSocketProcessor.java:328)
at org.atmosphere.websocket.DefaultWebSocketProcessor.invokeWebSocketProtocol(DefaultWebSocketProcessor.java:425)
at org.atmosphere.container.JSR356Endpoint$1.onMessage(JSR356Endpoint.java:214)
at org.atmosphere.container.JSR356Endpoint$1.onMessage(JSR356Endpoint.java:211)
at org.apache.tomcat.websocket.WsFrameBase.sendMessageText(WsFrameBase.java:399)
at org.apache.tomcat.websocket.WsFrameBase.processDataText(WsFrameBase.java:500)
at org.apache.tomcat.websocket.WsFrameBase.processData(WsFrameBase.java:295)
at org.apache.tomcat.websocket.WsFrameBase.processInputBuffer(WsFrameBase.java:131)
at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:71)
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler$WsReadListener.onDataAvailable(WsHttpUpgradeHandler.java:185)
at org.apache.coyote.http11.upgrade.AbstractServletInputStream.onDataAvailable(AbstractServletInputStream.java:198)
at org.apache.coyote.http11.upgrade.AbstractProcessor.upgradeDispatch(AbstractProcessor.java:96)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:647)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
We don’t see it with other browser types. That is, when using Chrome and Firefox at least, no such exception occurs.
It appears related to when we have a button that opens up a popup window with downloaded content (…/APP/connector/… URL). The popup opens and shows the content as expected, but gets this exception as well.