When running Outbound REST or SOAP Message integrations via a MID Server, the ECC Queue input may be set as:
This applies to the scripting API and also applies to the messages created by the 'Test' related link on REST or SOAP Message method definition forms.
This error really means "No Discovery Sensor Defined". Discovery was why the MID Server was designed, and at that time the only sensor business rule was "Discovery - Sensors" and this error comes from that. All other MID Server probes for SystemCommand etc. had ECC Queue output payload parameter skip_sensors=true used so that "Discovery - Sensors" was skipped.
All subsequent new applications and features that leverage Discovery's MID Server should be setting the ECC Parameter skip_sensors=true as well, so that Discovery - Sensors doesn't attempt to process the result from the probe. Most do. Some don't.
When scripting SOAPMessageV2 or RESTMessageV2, you should always set the skip_sensor=true parameter, even if you have created your own ecc_queue business rule sensor for the message.
This is done with the setEccParamater() method of the APIs. See the docs:
var sm = new sn_ws.RESTMessageV2("Yahoo Finance", "get"); sm.setBasicAuth("admin","admin"); sm.setStringParameter("symbol", "NOW"); sm.setStringParameterNoEscape("xml_data","<data>test</data>"); sm.setMIDServer('mid_server_name'); sm.setEccParameter("skip_sensor","true"); // prevent Discovery sensors running for the ECC input sm.setEccCorrelator("rest.yahoo"); // unique identifier for this message, used by the custom sensor business rule for matching the ecc_queue input sm.executeAsync(); // send the ECC queue output and end this script. The Sensor business rule will carry on once the response arrives back from the MID Server
Please note the correct use of executeAsync() when a MID Server is involved in that example.
After 'solving' this by adding the skip_sensor attribute, you may now find all your input records are stuck in Ready state. That's probably correct, if you don't have any kind of Sensor to set it as processed.
For more on those 2 points, see:
This issue is related to the following confirmed problem ticket:
KB0727122 Discovery - Sensors business rule will run for non-Discovery ecc_queue inputs