diff --git a/superset/mcp_service/chart/tool/update_chart.py b/superset/mcp_service/chart/tool/update_chart.py
index 88fc5e28849..caefae1b9d0 100755
--- a/superset/mcp_service/chart/tool/update_chart.py
+++ b/superset/mcp_service/chart/tool/update_chart.py
@@ -196,7 +196,8 @@ def _validate_update_against_dataset(
             }
         )
 
-    # Column existence + fuzzy-match validation (mirrors generate_chart pipeline layer 2)
+    # Column existence + fuzzy-match validation
+    # (mirrors generate_chart pipeline layer 2)
     from superset.mcp_service.chart.validation.dataset_validator import DatasetValidator
 
     is_col_valid, col_error = DatasetValidator.validate_against_dataset(
@@ -414,11 +415,13 @@ async def update_chart(  # noqa: C901
 
         # Normalize column case to match dataset canonical names
         # (mirrors generate_chart pipeline layer 4)
-        if parsed_config is not None and getattr(chart, "datasource_id", None) is not None:
+        chart_datasource_id = getattr(chart, "datasource_id", None)
+        if parsed_config is not None and chart_datasource_id is not None:
             from superset.mcp_service.chart.validation.dataset_validator import (
                 DatasetValidator,
                 NORMALIZATION_EXCEPTIONS,
             )
+
             try:
                 parsed_config = DatasetValidator.normalize_column_names(
                     parsed_config, chart.datasource_id
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py b/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
old mode 100644
new mode 100755
index c504d8bca59..21e2286fb6f
--- a/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
@@ -1175,6 +1175,11 @@ class TestUpdateChartValidationGate:
     )
     @patch("superset.daos.chart.ChartDAO.find_by_id", new_callable=Mock)
     @patch("superset.db.session")
+    @patch(
+        "superset.mcp_service.chart.validation.dataset_validator"
+        ".DatasetValidator.validate_against_dataset",
+        new=Mock(return_value=(True, None)),
+    )
     @pytest.mark.asyncio
     async def test_preview_path_validation_failure_skips_cache(
         self,
@@ -1238,6 +1243,11 @@ class TestUpdateChartValidationGate:
     )
     @patch("superset.daos.chart.ChartDAO.find_by_id", new_callable=Mock)
     @patch("superset.db.session")
+    @patch(
+        "superset.mcp_service.chart.validation.dataset_validator"
+        ".DatasetValidator.validate_against_dataset",
+        new=Mock(return_value=(True, None)),
+    )
     @pytest.mark.asyncio
     async def test_persist_path_validation_failure_skips_db_write(
         self,