diff --git a/ai21/models/responses/run_response.py b/ai21/models/responses/run_response.py
index 0a260235..63ae4400 100644
--- a/ai21/models/responses/run_response.py
+++ b/ai21/models/responses/run_response.py
@@ -17,3 +17,4 @@ class RunResponse(AI21BaseModel):
     optimization: Optimization
     execution_id: Optional[str] = None
     required_action: Optional[RequiredAction] = None
+    error: Optional[str] = None