WSO2 ESB ERROR - ClientUtils The system cannot infer the transport information

After I tested my proxy service in ESB, I got the following error when it tried to save the message into a file.

ERROR - ClientUtils The system cannot infer the transport information from the vfs:file:///C:/Temp URL.  

The source code I am using is as below:

 <?xml version="1.0" encoding="UTF-8"?>  
 <sequence name="saveToFS" trace="disable" xmlns="http://ws.apache.org/ns/synapse">  
  <property  
   expression="fn:concat(get-property('SYSTEM_DATE', 'yyMMddHHmmss'), '-', get-property('filename'), '.xml')"  
   name="transport.vfs.ReplyFileName" scope="transport" type="STRING"/>  
  <property name="OUT_ONLY" scope="default" type="STRING" value="true"/>  
  <call>  
   <endpoint>  
    <address trace="disable" uri="vfs:file:///c:/Temp"/>  
   </endpoint>  
  </call>  
  <log level="custom">  
   <property name="msg" value="File Saved to Disk"/>  
  </log>  
 </sequence>  

After research, I found the error is I need to enable vfs transport in the configuration file.
I enabled the following lines in wso2esb-4.9.0\repository\conf\axis2\axis.xml file. Then it works.

  <transportReceiver name="vfs" class="org.apache.synapse.transport.vfs.VFSTransportListener"/>  
 ......  
 <transportSender name="vfs" class="org.apache.synapse.transport.vfs.VFSTransportSender"/>