LangGraph dev/studio error: "Failed to fetch assistants: Not Found" – but agent works on frontend

[farouk09]

Hi, I'm working on creating a ReAct agent using LangGraph. The agent works as expected in the frontend at https://agentchat.vercel.app/, but when I use langgraph dev and open LangGraph Studio, I get the following error:

Error: Failed to fetch assistants: Not Found
In the terminal, I also see this warning:

[py.warnings] api_variant=local_dev langgraph_api_version=0.2.72 method=GET path=/assistants/{assistant_id}/schemas thread_name=MainThread
2025-06-30T13:55:54.692361Z [warning  ] .../langgraph_api/api/assistants.py:59: 
PydanticDeprecatedSince20: The `__fields__` attribute is deprecated, use `model_fields` instead. 
Deprecated in Pydantic V2.0 to be removed in V3.0. 
See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.10/migration/

Here is a simplified version of my code:

# Define the state graph
retrieval_graph = StateGraph(MessagesState)

agent = create_react_agent(
    llm,
    tools=tools,
    prompt=create_prompt
)

retrieval_graph.add_node("agent", agent)
retrieval_graph.add_edge(START, "agent")

retrieval_graph = retrieval_graph.compile()

I’m not sure if this is an issue with my code or an incompatibility between LangGraph Studio and my setup. Do I need to register the assistant or define something additional for Studio to recognize it?

[project]
name = "retrieval-agent"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.11"
dependencies = [
    "bs4>=0.0.2",
    "faiss-cpu>=1.10.0",
    "google-api-python-client>=2.174.0",
    "google-auth>=2.40.3",
    "google-auth-oauthlib>=1.2.2",
    "langchain-community>=0.3.20",
    "langchain-huggingface==0.3.0",
    "langchain-ollama>=0.3.0",
    "langchain-openai==0.3.18",
    "langgraph-api==0.2.72",
    "langgraph-cli[inmem]>=0.1.79",
    "langmem>=0.0.27",
    "mem0ai==0.1.102",
    "setuptools>=78.0.2",
    "vllm>=0.8.1",
]

Any help would be appreciated!

[farouk09]

I'm having this warnings any solutions ?

[autonoma-srl]

same here, langgraph studio can crud but if you query from langgraph api ran from langgraph dev it says 404, auth works tho