Update tagged union message with clearer description (#2516)

boto · Oct 4, 2021 · 1a50773 · 1a50773
1 parent ee45929
commit 1a50773
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/botocore/parsers.py b/botocore/parsers.py
@@ -335,8 +335,8 @@ def _has_unknown_tagged_union_member(self, shape, value):
         if shape.is_tagged_union:
             if len(value) != 1:
                 error_msg = (
-                    "Invalid service response: %s must only have one member "
-                    "set."
+                    "Invalid service response: %s must have one and only "
+                    "one member set."
                 )
                 raise ResponseParserError(error_msg % shape.name)
             tag = self._get_first_key(value)