diff --git a/romancal/stpipe/core.py b/romancal/stpipe/core.py
index 651f522bb..4a1cea11a 100644
--- a/romancal/stpipe/core.py
+++ b/romancal/stpipe/core.py
@@ -37,6 +37,9 @@ class RomanStep(Step):
 
     _log_records_formatter = _LOG_FORMATTER
 
+    def __call__(self, *args):
+        raise Exception()
+
     @classmethod
     def _datamodels_open(cls, init, **kwargs):
         """