diff --git a/step/lib.php b/step/lib.php
index e9ee290c45cbe42baa109f9291e5cf933a88ba09..03018d932e729e91023fd483b5d5c21582b5de25 100644
--- a/step/lib.php
+++ b/step/lib.php
@@ -64,7 +64,7 @@ abstract class libbase {
      * @return step_response
      */
     public function process_waiting_course($processid, $instanceid, $course) {
-        return step_response::proceed();
+        throw new \coding_exception("Processing of waiting courses is not supported for this workflow step.");
     }
 
     /**