diff --git a/python/ray/serve/schema.py b/python/ray/serve/schema.py
index 5435e0ed9bde..79b54787acee 100644
--- a/python/ray/serve/schema.py
+++ b/python/ray/serve/schema.py
@@ -947,10 +947,12 @@ class DeploymentDetails(BaseModel, extra=Extra.forbid, frozen=True):
     def deployment_route_prefix_not_set(cls, v: DeploymentSchema):
         # Route prefix should not be set at the deployment level. Deployment-level route
         # prefix is outdated, there should be one route prefix per application
-        if "route_prefix" in v.dict(exclude_unset=True):
+        if (
+            "route_prefix" in v.__fields_set__
+        ):  # in Pydantic v2, this becomes `in v.model_fields_set`
             raise ValueError(
                 "Unexpectedly found a deployment-level route_prefix in the "
-                f'deployment_config for deployment "{cls.name}". The route_prefix in '
+                f'deployment_config for deployment "{v.name}". The route_prefix in '
                 "deployment_config within DeploymentDetails should not be set; please "
                 "set it at the application level."
             )