diff --git a/planner/core/expression_rewriter.go b/planner/core/expression_rewriter.go
index 3d0b48cb32897..ee07adf4f9401 100644
--- a/planner/core/expression_rewriter.go
+++ b/planner/core/expression_rewriter.go
@@ -322,7 +322,7 @@ func (er *expressionRewriter) Enter(inNode ast.Node) (ast.Node, bool) {
 			index, ok = er.windowMap[v]
 		}
 		if !ok {
-			er.err = ErrWindowInvalidWindowFuncUse.GenWithStackByArgs(v.F)
+			er.err = ErrWindowInvalidWindowFuncUse.GenWithStackByArgs(strings.ToLower(v.F))
 			return inNode, true
 		}
 		er.ctxStack = append(er.ctxStack, er.schema.Columns[index])
diff --git a/planner/core/logical_plan_builder.go b/planner/core/logical_plan_builder.go
index 15d259f6ed60b..72549fef0448a 100644
--- a/planner/core/logical_plan_builder.go
+++ b/planner/core/logical_plan_builder.go
@@ -1240,7 +1240,7 @@ func (a *havingWindowAndOrderbyExprResolver) Leave(n ast.Node) (node ast.Node, o
 	case *ast.WindowFuncExpr:
 		a.inWindowFunc = false
 		if a.curClause == havingClause {
-			a.err = ErrWindowInvalidWindowFuncUse.GenWithStackByArgs(v.F)
+			a.err = ErrWindowInvalidWindowFuncUse.GenWithStackByArgs(strings.ToLower(v.F))
 			return node, false
 		}
 		if a.curClause == orderByClause {
diff --git a/planner/core/logical_plan_test.go b/planner/core/logical_plan_test.go
index dd83b98ae48f1..dfba5b4cc54dc 100644
--- a/planner/core/logical_plan_test.go
+++ b/planner/core/logical_plan_test.go
@@ -2327,6 +2327,14 @@ func (s *testPlanSuite) TestWindowFunction(c *C) {
 			sql:    "delete from t order by (sum(a) over())",
 			result: "[planner:3593]You cannot use the window function 'sum' in this context.'",
 		},
+		{
+			sql:    "delete from t order by (SUM(a) over())",
+			result: "[planner:3593]You cannot use the window function 'sum' in this context.'",
+		},
+		{
+			sql:    "SELECT * from t having ROW_NUMBER() over()",
+			result: "[planner:3593]You cannot use the window function 'row_number' in this context.'",
+		},
 		{
 			// The best execution order should be (a,c), (a, b, c), (a, b), (), it requires only 2 sort operations.
 			sql:    "select sum(a) over (partition by a order by b), sum(b) over (order by a, b, c), sum(c) over(partition by a order by c), sum(d) over() from t",