2479908 - The MessageServlet URL failed with "500 Internal Server Error"

You installed a new PO/AEX system and have run the CTC wizard successfully.
When you access the MessageServlet URL http://<host>:<port>/XISOAPAdapter/MessageServlet?ximessage=true, it failed with error:
HTTP 500 internal server error

You have taken the following check:

1. From defaultTrace, the following log could be found:
   
   Cannot process an HTTP request to servlet [MessageServlet] in [XISOAPAdapter] web application.
   [EXCEPTION]
   null; nested exception caused by:
   com.sap.engine.interfaces.messaging.api.exception.MessagingException: Connection SOAP_http://sap.com/xi/XI/Systemcannot be created as it was not registered before!
   at com.sap.engine.messaging.impl.api.ConnectionFactoryImpl.checkConnectionRegistration(ConnectionFactoryImpl.java:259)
   at com.sap.engine.messaging.impl.api.ConnectionFactoryImpl.createConnection(ConnectionFactoryImpl.java:113)
   at com.sap.engine.messaging.impl.api.ConnectionFactoryImpl.createConnection(ConnectionFactoryImpl.java:99)
   at com.sap.aii.adapter.soap.web.SOAPHandler.<init>(SOAPHandler.java:160)
   
   
2. Check the following SOAP applications from NWA -> Start & Stop, they are in the started status:
• com.sap.aii.adapter.soap.app
• com.sap.aii.adapter.soap.lib
  
  
3. Check the CPACache history, there is no successful CPACache update in the system (https://<host>:<port>/CPACache/).

• SAP NetWeaver
• SAP Process Integration

MessageServlet, XISOAPAdapter, 500 Internal Server Error, 500, CPACache, SOAP, SAP_BASIS, ESR content, initial, SLD, Process Integration 7.0, PI 7.0, PI 7.01, PI 7.02, Process Integration 7.10, PI 7.10, Process Integration 7.11, PI 7.11, Process Integration 7.30, PI 7.30, Process Integration 7.31, PI 7.31, Process Orchestration 7.40, PI 7.40, PO 7.40, Process Orchestration 7.50, PI 7.50, PO 7.50, NetWeaver, XI. , KBA , BC-XI-CON-SOP , SOAP Adapter , BC-XI-CON-AFW , J2EE Adapter Framework , Problem