diff --git a/src/expr/src/vector_op/array_length.rs b/src/expr/src/vector_op/array_length.rs
index 890ef368df7b1..4b44b2ac4d9b4 100644
--- a/src/expr/src/vector_op/array_length.rs
+++ b/src/expr/src/vector_op/array_length.rs
@@ -56,7 +56,7 @@ use crate::ExprError;
 /// ----
 /// 1
 ///
-/// query error type unknown
+/// query error Cannot implicitly cast
 /// select array_length(null);
 /// ```
 #[function("array_length(list) -> int32")]
diff --git a/src/expr/src/vector_op/cardinality.rs b/src/expr/src/vector_op/cardinality.rs
index 07481a5eef854..d482da3b30d39 100644
--- a/src/expr/src/vector_op/cardinality.rs
+++ b/src/expr/src/vector_op/cardinality.rs
@@ -56,7 +56,7 @@ use crate::ExprError;
 /// ----
 /// 1
 ///
-/// query error type unknown
+/// query error Cannot implicitly cast
 /// select cardinality(null);
 /// ```
 #[function("cardinality(list) -> int32")]