2734023 - AS Java Portal Iview displays "HTTP 500" error - rmi_p4.P4IOException - connection refused - client with this banner already exists

• A specific AS Java Portal application (e.g. EmployeeTimesheets) shows "HTTP 500" error:
   
  

• defaultTrace files shows the relevant error from the timestamp:
    
  [...]
  500 Internal Server Error is returned for HTTP request [https://<host1>:443/webdynpro/resources/sap.com/pb/PageBuilder]:
  component [forwardServlet],
  [...]
  [EXCEPTION]
  [...]
  FPN failed to lookup for remote object '<...>/com.<vendor>.employee_timesheets_2'
  [...]
  com.sap.portal.fpn.exception.unchecked.RemoteInfrastructureFailureException: Could not get to the remote side
  [...]
  Caused by: javax.naming.NamingException: Exception while trying to get InitialContext. [Root exception is com.sap.engine.interfaces.cross.DestinationException: Cannot establish connection with any of the available profiles. Check if server is started, access point for the protocol is available, and IP/Host name is accessible on the network.
  URL=p4://<host2>:50104, protocol=p4(None), Reason: com.sap.engine.services.rmi_p4.P4IOException: ;]
  [...]
  Caused by: com.sap.engine.interfaces.cross.DestinationException: Cannot establish connection with any of the available profiles. Check if server is started, access point for the protocol is available, and IP/Host name is accessible on the network.
  URL=p4://<host2>:50104, protocol=p4(None), Reason: com.sap.engine.services.rmi_p4.P4IOException: ;
  [...]
  Caused by: com.sap.engine.services.rmi_p4.P4IOException:
  [...]
  Caused by: java.io.IOException: Failed to open a connection to 1:0:<host2>:50104, reason: connection refused
  [...]
    
• dev_icm of host1 shows parallel the following:
  
  [Thr 8092] *** WARNING => P4PlugInReadHandler(id=4/11373): P4RecvHandShake failed: Network error (NI)(-8) [p4_plg.c 1263]
  [...]
  [Thr 8092] *** ERROR => client with this banner already exists: 1:<host2>:50104 {0010bc1a} [p4_plg.c 3548]
  [...]

• SAP NetWeaver Application Server Java
• Enterprise Portal
• P4 connection between two AS Java Systems

EmployeeTimesheets, Employee Timesheets, Enterprise Portal, HTTP 500, 500 internal server error, client with this banner already exists, P4RecvHandShake failed, rmi_p4.P4IOException, connection refused , KBA , EP-PIN-FPN , Federated Portal Network , BC-CST-IC , Internet Communication Manager , BC-JAS-COR-RMT , RMI, P4, CORBA, IIOP , Problem