diff --git a/lib/galaxy/workflow/refactor/schema.py b/lib/galaxy/workflow/refactor/schema.py
index b5b62553e55..a4ca1800242 100644
--- a/lib/galaxy/workflow/refactor/schema.py
+++ b/lib/galaxy/workflow/refactor/schema.py
@@ -241,7 +241,14 @@ union_action_classes = Union[
 
 ACTION_CLASSES_BY_TYPE = {}
 for action_class in union_action_classes.__args__:  # type: ignore
-    action_type = action_class.schema()["properties"]["action_type"]["const"]
+    action_type_def = action_class.schema()["properties"]["action_type"]
+    try:
+        # pydantic 1.8
+        action_type = action_type_def["enum"][0]
+    except KeyError:
+        # pydantic 1.7
+        action_type = action_type_def["const"]
+
     ACTION_CLASSES_BY_TYPE[action_type] = action_class