diff --git a/monai/deploy/core/app_context.py b/monai/deploy/core/app_context.py
index bb8751b2..16e430fc 100644
--- a/monai/deploy/core/app_context.py
+++ b/monai/deploy/core/app_context.py
@@ -27,7 +27,7 @@ def __init__(self, args: Dict[str, str], runtime_env: Optional[RuntimeEnv] = Non
         self.runtime_env = runtime_env or RuntimeEnv()
 
         self._model_loaded = False  # If it has tried to load the models.
-        self.model_path = None  # To be set next.
+        self.model_path = ""  # To be set next.
         self.update(args)
 
     def update(self, args: Dict[str, str]):