diff --git a/src/common/tools/grpc/Constraints.py b/src/common/tools/grpc/Constraints.py
index a395f4cc303185181094fbf5aa434cf3ccc075dd..9b8cea19fa53d697f0f61ca21d4e3963fdd855db 100644
--- a/src/common/tools/grpc/Constraints.py
+++ b/src/common/tools/grpc/Constraints.py
@@ -16,6 +16,7 @@
 # Ref: https://datatracker.ietf.org/doc/html/rfc8466
 
 
+import json
 from typing import Any, Dict, List, Optional, Tuple
 from common.proto.context_pb2 import Constraint, ConstraintActionEnum, EndPointId, QoSProfileId
 from common.tools.grpc.Tools import grpc_message_to_json_string