java.lang.NullPointerException in BPEL Invoke

You might get the following error while invoking a service from BPEL

<bpelFault>
   <faultType>0</faultType>
   <remoteFault>
      <part name="summary">
         <summary>java.lang.NullPointerException</summary>
      </part>
      <part name="detail">
         <detail>null</detail>
      </part>
   </remoteFault>
</bpelFault>

This means that the service is not available, or atleast the bpel is not able to find the service operation.

But you might observe the service works fine directly.
This happens when the WSDL in the MDS is not updated with the right one (In my case, the service that I'm invoking is an OSB Service in some other machine)

Sometimes, the MDS doesn't get properly updated during the deployment. To confirm, create an MDS connection in JDev and check if the wsdl/xsd's are updated.

If not, then refresh the MDS / clear cache, and redeploy. It works now.