Application not available through mod_cluster with errors saying "Can't read host alias"

Solution Verified - Updated -

Issue

  • I have several nodes connected to mod_cluster. They're all shown on the manager page, but some nodes are not showing any contexts and applications are not responsive on these nodes through Apache/mod_cluster.
  • The JBoss server.log continuously shows messages like the following:
ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (ContainerBackgroundProcessor[StandardEngine[jboss.web]]) Error [MEM: MEM: Can't read host alias: {4}] sending command ENABLE-APP to proxy 127.0.0.1:6666, configuration will be reset
  • Seeing the following error messages repeated:
ERROR [org.jboss.modcluster] (ServerService Thread Pool -- 88) MODCLUSTER000042: Error MEM send
ing ENABLE-APP command to 127.0.0.1:6666, configuration will be reset: MEM: Can't update or insert host alias

Environment

  • JBoss Enterprise Application Platform (EAP)
  • JBoss Enterprise Web Server (EWS)
    • Apache httpd
    • mod_cluster

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