SENDER RFC Adapter Error: request was <null> while trying to extract it

Hi All,

I have a scenario in which a SAP ERP sends a synchronous request through RFC adapter. The scenario is working but sometimes I get the error below. Any idea? Couldn't find anything on SDN.

Error in processing caused by: java.lang.Exception: RfcServer[CC_ECC_SEND]1[AFSenderD] request was <null> while trying to extract it.