diff --git a/superset-frontend/src/visualizations/TimeTable/transformProps.js b/superset-frontend/src/visualizations/TimeTable/transformProps.js
index a49c421b0c4..93e0e7df70a 100644
--- a/superset-frontend/src/visualizations/TimeTable/transformProps.js
+++ b/superset-frontend/src/visualizations/TimeTable/transformProps.js
@@ -20,7 +20,7 @@ export default function transformProps(chartProps) {
   const { height, datasource, formData, queriesData } = chartProps;
   const { columnCollection = [], groupby, metrics, url } = formData;
   const { records, columns } = queriesData[0].data;
-  const isGroupBy = groupby.length > 0;
+  const isGroupBy = groupby?.length > 0;
 
   // When there is a "group by",
   // each row in the table is a database column
diff --git a/superset/viz.py b/superset/viz.py
index db88383115b..9235f6c3a8c 100644
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -803,7 +803,7 @@ class TimeTableViz(BaseViz):
         return dict(
             records=pt.to_dict(orient="index"),
             columns=list(pt.columns),
-            is_group_by=len(fd.get("groupby", [])) > 0,
+            is_group_by=True if fd.get("groupby") else False,
         )