EJB over HTTP fails going through Apache httpd proxied to JBoss EAP via AJP

Issue

• Calls or messaging do not work

• Log shows the following exception

  Exception in thread "main" javax.ejb.EJBException: java.io.IOException: UT001033: Invalid connection state
    at org.jboss.ejb.client.EJBInvocationHandler.invoke(EJBInvocationHandler.java:207)
    at org.jboss.ejb.client.EJBInvocationHandler.invoke(EJBInvocationHandler.java:112)
    at com.sun.proxy.$Proxy0.logMessageAndReturnJBossNodeNameWithDelay(Unknown Source)
    at org.jboss.playground.client.CommonClient.invokeSimpleRemote(CommonClient.java:52)
    at org.jboss.playground.client.EjbOverHttpWithWildflyConfigXmlEjbClient.main(EjbOverHttpWithWildflyConfigXmlEjbClient.java:54)
  Caused by: java.io.IOException: UT001033: Invalid connection state
    at io.undertow.client.http.HttpClientConnection.sendRequest(HttpClientConnection.java:336)
    at org.wildfly.httpclient.common.HttpTargetContext.sendRequestInternal(HttpTargetContext.java:165)
    at org.wildfly.httpclient.common.HttpTargetContext$1$1.lambda$null$0(HttpTargetContext.java:183)
    at org.wildfly.httpclient.common.HttpConnectionPool$1.completed(HttpConnectionPool.java:157)
    at org.wildfly.httpclient.common.HttpConnectionPool$1.completed(HttpConnectionPool.java:151)
    at io.undertow.client.http.HttpClientProvider.handleConnected(HttpClientProvider.java:156)
    at io.undertow.client.http.HttpClientProvider.access$000(HttpClientProvider.java:51)
    at io.undertow.client.http.HttpClientProvider$2.handleEvent(HttpClientProvider.java:127)
    at io.undertow.client.http.HttpClientProvider$2.handleEvent(HttpClientProvider.java:124)
    at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
    at org.xnio.nio.WorkerThread$ConnectHandle.handleReady(WorkerThread.java:333)
    at org.xnio.nio.WorkerThread.run(WorkerThread.java:591)