Update error message in evaluation runner (#13296)

libs/langchain/langchain/smith/evaluation/runner_utils.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import functools
 import inspect
 import logging
+import uuid
 from enum import Enum
 from typing import (
     TYPE_CHECKING,
@@ -23,6 +24,8 @@ from langsmith.client import Client
 from langsmith.evaluation import RunEvaluator
 from langsmith.run_helpers import as_runnable, is_traceable_function
 from langsmith.schemas import Dataset, DataType, Example
+from langsmith.utils import LangSmithError
+from requests import HTTPError
 
 from langchain._api import warn_deprecated
 from langchain.callbacks.manager import Callbacks
@@ -880,11 +883,19 @@ def _prepare_eval_run(
             reference_dataset_id=dataset.id,
             project_extra={"metadata": project_metadata} if project_metadata else {},
         )
-    except ValueError as e:
+    except (HTTPError, ValueError, LangSmithError) as e:
         if "already exists " not in str(e):
             raise e
+        uid = uuid.uuid4()
+        example_msg = f"""
+run_on_dataset(
+    ...
+    project_name="{project_name} - {uid}", # Update since {project_name} already exists
+)
+"""
         raise ValueError(
-            f"Project {project_name} already exists. Please use a different name."
+            f"Test project {project_name} already exists. Please use a different name:"
+            f"\n\n{example_msg}"
         )
     print(
         f"View the evaluation results for project '{project_name}'"