diff --git a/server/routes/query_assist/routes.ts b/server/routes/query_assist/routes.ts
index a3e5b0bedd..d34d5256db 100644
--- a/server/routes/query_assist/routes.ts
+++ b/server/routes/query_assist/routes.ts
@@ -83,11 +83,15 @@ export function registerQueryAssistRoutes(router: IRouter) {
         if (
           isResponseError(error) &&
           error.statusCode === 400 &&
-          error.body.includes(ERROR_DETAILS.GUARDRAILS_TRIGGERED)
+          // on opensearch >= 2.17, error.body is an object https://github.com/opensearch-project/ml-commons/pull/2858
+          JSON.stringify(error.body).includes(ERROR_DETAILS.GUARDRAILS_TRIGGERED)
         ) {
           return response.badRequest({ body: ERROR_DETAILS.GUARDRAILS_TRIGGERED });
         }
-        return response.custom({ statusCode: error.statusCode || 500, body: error.message });
+        return response.custom({
+          statusCode: error.statusCode || 500,
+          body: typeof error.body === 'string' ? error.body : JSON.stringify(error.body),
+        });
       }
     }
   );
@@ -155,11 +159,15 @@ export function registerQueryAssistRoutes(router: IRouter) {
         if (
           isResponseError(error) &&
           error.statusCode === 400 &&
-          error.body.includes(ERROR_DETAILS.GUARDRAILS_TRIGGERED)
+          // on opensearch >= 2.17, error.body is an object https://github.com/opensearch-project/ml-commons/pull/2858
+          JSON.stringify(error.body).includes(ERROR_DETAILS.GUARDRAILS_TRIGGERED)
         ) {
           return response.badRequest({ body: ERROR_DETAILS.GUARDRAILS_TRIGGERED });
         }
-        return response.custom({ statusCode: error.statusCode || 500, body: error.message });
+        return response.custom({
+          statusCode: error.statusCode || 500,
+          body: typeof error.body === 'string' ? error.body : JSON.stringify(error.body),
+        });
       }
     }
   );