diff --git a/sdks/python/apache_beam/yaml/yaml_mapping.py b/sdks/python/apache_beam/yaml/yaml_mapping.py
index 3bef1a0a1101..9f92f59f42b6 100644
--- a/sdks/python/apache_beam/yaml/yaml_mapping.py
+++ b/sdks/python/apache_beam/yaml/yaml_mapping.py
@@ -467,7 +467,9 @@ def expand(self, pcoll):
           break
       else:
         raise ValueError(
-            f"No field name matches one of {self._ERROR_FIELD_NAMES}")
+            'The input to this transform does not appear to be an error ' +
+            "output.  Expected a schema'd input with a field named " +
+            ' or '.join(repr(fld) for fld in self._ERROR_FIELD_NAMES))
 
     if fld is None:
       # This handles with_exception_handling() that returns bare tuples.