diff --git a/pkg/expression/builtin_json.go b/pkg/expression/builtin_json.go
index 86961ee19e179..32f21d788998b 100644
--- a/pkg/expression/builtin_json.go
+++ b/pkg/expression/builtin_json.go
@@ -1770,10 +1770,6 @@ func (b *builtinJSONLengthSig) evalInt(ctx EvalContext, row chunk.Row) (res int6
 		return res, isNull, err
 	}
 
-	if obj.TypeCode != types.JSONTypeCodeObject && obj.TypeCode != types.JSONTypeCodeArray {
-		return 1, false, nil
-	}
-
 	if len(b.args) == 2 {
 		path, isNull, err := b.args[1].EvalString(ctx, row)
 		if isNull || err != nil {
@@ -1793,9 +1789,10 @@ func (b *builtinJSONLengthSig) evalInt(ctx EvalContext, row chunk.Row) (res int6
 		if !exists {
 			return res, true, nil
 		}
-		if obj.TypeCode != types.JSONTypeCodeObject && obj.TypeCode != types.JSONTypeCodeArray {
-			return 1, false, nil
-		}
+	}
+
+	if obj.TypeCode != types.JSONTypeCodeObject && obj.TypeCode != types.JSONTypeCodeArray {
+		return 1, false, nil
 	}
 	return int64(obj.GetElemCount()), false, nil
 }
diff --git a/pkg/expression/builtin_json_test.go b/pkg/expression/builtin_json_test.go
index 95ce9414a7afa..60561566730f7 100644
--- a/pkg/expression/builtin_json_test.go
+++ b/pkg/expression/builtin_json_test.go
@@ -647,8 +647,8 @@ func TestJSONLength(t *testing.T) {
 		{[]any{`-1`}, 1, true},
 		{[]any{`1.1`}, 1, true},
 		{[]any{`"1"`}, 1, true},
-		{[]any{`"1"`, "$.a"}, 1, true},
-		{[]any{`null`, "$.a"}, 1, true},
+		{[]any{`"1"`, "$.a"}, nil, true},
+		{[]any{`null`, "$.a"}, nil, true},
 		// Tests nil arguments
 		{[]any{nil}, nil, true},
 		{[]any{nil, "a"}, nil, true},
diff --git a/pkg/expression/builtin_json_vec.go b/pkg/expression/builtin_json_vec.go
index 84dab07ef6e29..dbb4d443d26b4 100644
--- a/pkg/expression/builtin_json_vec.go
+++ b/pkg/expression/builtin_json_vec.go
@@ -814,6 +814,9 @@ func (b *builtinJSONLengthSig) vectorized() bool {
 func (b *builtinJSONLengthSig) vecEvalInt(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error {
 	nr := input.NumRows()
 
+	result.ResizeInt64(nr, false)
+	resI64s := result.Int64s()
+
 	jsonBuf, err := b.bufAllocator.get()
 	if err != nil {
 		return err
@@ -822,8 +825,7 @@ func (b *builtinJSONLengthSig) vecEvalInt(ctx EvalContext, input *chunk.Chunk, r
 	if err := b.args[0].VecEvalJSON(ctx, input, jsonBuf); err != nil {
 		return err
 	}
-	result.ResizeInt64(nr, false)
-	resI64s := result.Int64s()
+	result.MergeNulls(jsonBuf)
 
 	if len(b.args) == 2 {
 		pathBuf, err := b.bufAllocator.get()
@@ -834,23 +836,12 @@ func (b *builtinJSONLengthSig) vecEvalInt(ctx EvalContext, input *chunk.Chunk, r
 		if err := b.args[1].VecEvalString(ctx, input, pathBuf); err != nil {
 			return err
 		}
+		result.MergeNulls(pathBuf)
 
-		result.MergeNulls(jsonBuf)
 		for i := 0; i < nr; i++ {
 			if result.IsNull(i) {
 				continue
 			}
-			jsonItem := jsonBuf.GetJSON(i)
-
-			if jsonItem.TypeCode != types.JSONTypeCodeObject && jsonItem.TypeCode != types.JSONTypeCodeArray {
-				resI64s[i] = 1
-				continue
-			}
-
-			if pathBuf.IsNull(i) {
-				result.SetNull(i, true)
-				continue
-			}
 
 			pathExpr, err := types.ParseJSONPathExpr(pathBuf.GetString(i))
 			if err != nil {
@@ -860,6 +851,7 @@ func (b *builtinJSONLengthSig) vecEvalInt(ctx EvalContext, input *chunk.Chunk, r
 				return types.ErrInvalidJSONPathMultipleSelection
 			}
 
+			jsonItem := jsonBuf.GetJSON(i)
 			obj, exists := jsonItem.Extract([]types.JSONPathExpression{pathExpr})
 			if !exists {
 				result.SetNull(i, true)
@@ -872,7 +864,6 @@ func (b *builtinJSONLengthSig) vecEvalInt(ctx EvalContext, input *chunk.Chunk, r
 			resI64s[i] = int64(obj.GetElemCount())
 		}
 	} else {
-		result.MergeNulls(jsonBuf)
 		for i := 0; i < nr; i++ {
 			if result.IsNull(i) {
 				continue
diff --git a/tests/integrationtest/r/expression/json.result b/tests/integrationtest/r/expression/json.result
index 243a8388b0ab9..a2092ffe22376 100644
--- a/tests/integrationtest/r/expression/json.result
+++ b/tests/integrationtest/r/expression/json.result
@@ -429,9 +429,20 @@ json_length('{}'),
 json_length('[]'),
 json_length('{"a": 1}'),
 json_length('{"a": 1, "b": 2}'),
-json_length('[1, 2, 3]');
-json_length('1')	json_length('{}')	json_length('[]')	json_length('{"a": 1}')	json_length('{"a": 1, "b": 2}')	json_length('[1, 2, 3]')
-1	0	0	1	2	3
+json_length('[1, 2, 3]'),
+json_length('{}', '$'),
+json_length('1', '$'),
+json_length(null, '$'),
+json_length(null, 'fdfd'),
+json_length('{}', null),
+json_length('1', '$.a'),
+json_length('{}', '$.a');
+json_length('1')	json_length('{}')	json_length('[]')	json_length('{"a": 1}')	json_length('{"a": 1, "b": 2}')	json_length('[1, 2, 3]')	json_length('{}', '$')	json_length('1', '$')	json_length(null, '$')	json_length(null, 'fdfd')	json_length('{}', null)	json_length('1', '$.a')	json_length('{}', '$.a')
+1	0	0	1	2	3	0	1	NULL	NULL	NULL	NULL	NULL
+select json_length('{}', 'fsdfds');
+Error 3143 (42000): Invalid JSON path expression. The error is around character position 1.
+select json_length('1', 'fsdfds');
+Error 3143 (42000): Invalid JSON path expression. The error is around character position 1.
 select json_array(922337203685477580) =  json_array(922337203685477581);
 json_array(922337203685477580) =  json_array(922337203685477581)
 0
diff --git a/tests/integrationtest/t/expression/json.test b/tests/integrationtest/t/expression/json.test
index 6d6a0f6b250e0..005b3754d2553 100644
--- a/tests/integrationtest/t/expression/json.test
+++ b/tests/integrationtest/t/expression/json.test
@@ -248,7 +248,18 @@ select
 		json_length('[]'),
 		json_length('{"a": 1}'),
 		json_length('{"a": 1, "b": 2}'),
-		json_length('[1, 2, 3]');
+		json_length('[1, 2, 3]'),
+		json_length('{}', '$'),
+		json_length('1', '$'),
+		json_length(null, '$'),
+		json_length(null, 'fdfd'),
+		json_length('{}', null),
+		json_length('1', '$.a'),
+		json_length('{}', '$.a');
+-- error 3143
+select json_length('{}', 'fsdfds');
+-- error 3143
+select json_length('1', 'fsdfds');
 # issue 16267
 select json_array(922337203685477580) =  json_array(922337203685477581);