ADF Controller cannot find metadata for activity

Recently faced this error when working on ADF task flow which has a method call

Stack Trace::

<Oct 30, 2015 3:45:36 PM PDT> <Notice> <Stdout> <BEA-000000> <<Oct 30, 2015 3:45:36 PM PDT> <Error> <oracle.adfinternal.controller.application.AdfcExceptionHandler> <ADFC-50016> <ADFc: While handling an exception the application's exception handler threw a new exception.

oracle.adf.controller.activity.ActivityLogicException: ADFC-02013: The ADF Controller cannot find metadata for activity '/WEB-INF/taskflows/ervice/service-flow.xml#service-flow@methodName'.

at oracle.adfinternal.controller.util.Utils.createAndLogActivityLogicException(Utils.java:230)

at oracle.adfinternal.controller.engine.ControlFlowEngine.doRouting(ControlFlowEngine.java:1003)

at oracle.adfinternal.controller.engine.ControlFlowEngine.doRouting(ControlFlowEngine.java:853)

at oracle.adfinternal.controller.engine.ControlFlowEngine.invokeTaskFlow(ControlFlowEngine.java:245) at oracle.adfinternal.controller.application.RemoteTaskFlowCallRequestHandler.invokeTaskFlowByUrl(RemoteTaskFlowCallRequestHandler.java:99) at oracle.adfinternal.controller.application.RemoteTaskFlowCallRequestHandler.doCreateView(RemoteTaskFlowCallRequestHandler.java:64)

at oracle.adfinternal.controller.application.BaseRequestHandlerImpl.createView(BaseRequestHandlerImpl.java:57)

at org.apache.myfaces.trinidadinternal.application.ViewHandlerImpl.createView(ViewHandlerImpl.java:95) at oracle.webcenter.portalframework.sitestructure.handler.CustomViewHandler.createView(CustomViewHandler.java:137

at oracle.adfinternal.view.faces.lifecycle.LifecycleImpl._restoreView(LifecycleImpl.java:831)

at oracle.adfinternal.view.faces.lifecycle.LifecycleImpl._executePhase(LifecycleImpl.java:422)

at oracle.adfinternal.view.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:207)

at javax.faces.webapp.FacesServlet.service(FacesServlet.java:265)

at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)

Fix::
Found that the method outcome is empty. Given some value to method outcome and the above error is gone.