diff --git a/superset/sqllab/api.py b/superset/sqllab/api.py
index 6be378a9b..eeb95e6aa 100644
--- a/superset/sqllab/api.py
+++ b/superset/sqllab/api.py
@@ -343,7 +343,9 @@ class SqlLabRestApi(BaseSupersetApi):
         # return the result without special encoding
         return json_success(
             json.dumps(
-                result, default=utils.json_iso_dttm_ser, ignore_nan=True, encoding=None
+                result,
+                default=utils.json_iso_dttm_ser,
+                ignore_nan=True,
             ),
             200,
         )
diff --git a/superset/sqllab/execution_context_convertor.py b/superset/sqllab/execution_context_convertor.py
index 430db0d52..a1e7a86d0 100644
--- a/superset/sqllab/execution_context_convertor.py
+++ b/superset/sqllab/execution_context_convertor.py
@@ -60,7 +60,6 @@ class ExecutionContextConvertor:
                 ),
                 default=utils.pessimistic_json_iso_dttm_ser,
                 ignore_nan=True,
-                encoding=None,
             )
 
         return json.dumps(