LangSmith Studio can't connect to self-hosted LangGraph server on Railway - "origin is not allowed"

LangSmith Product Help
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1

I have a LangGraph server deployed on Railway that was working fine with LangSmith Studio until a few days ago. Now I’m getting this error:

Error: Failed to connect to Agent Server because the origin is not allowed. Connect to a different server or add the origin to the allowed origins list.

It works fine locally with langgraph dev. And it was also working fine in prod.The server itself is responding correctly, CORS headers are correct

Has something changed recently on LangSmith’s side regarding connecting to external/self-hosted servers? Any help would be appreciated!

1 Like
2

I can confirm that https://smith.langchain.com/studio/?baseUrl=http://serverenpoint no longer works. However, when you click “Connect to local server“, it opens a new window. Entering the base_url and adding the endpoint to the allowed origins(in Advanced Settings) fixes the issue. I successfully connected to the endpoint.

3

It worked. Thank you

4

Does this work with –tunnel enable? I tried using the local host as endpoint and the cloudflare url as endpoint, both doesn’t work.

5

Yes, I just tried it. It seems to work with the following settings:

Ekran görüntüsü 2025-12-18 160911
Ekran görüntüsü 2025-12-18 160911734×843 53.2 KB

I followed the steps Run a local server - Docs by LangChain .

Here is the output of pip freeze:

Editable install with no version control (agent==0.0.1)

-e /home/pi/xxx
annotated-types==0.7.0
anyio==4.12.0
blockbuster==1.5.26
certifi==2025.11.12
cffi==2.0.0
charset-normalizer==3.4.4
click==8.3.1
cloudpickle==3.1.2
cryptography==46.0.3
forbiddenfruit==0.1.4
googleapis-common-protos==1.72.0
grpcio==1.76.0
grpcio-tools==1.75.1
h11==0.16.0
httpcore==1.0.9
httpx==0.28.1
idna==3.11
importlib_metadata==8.7.0
jsonpatch==1.33
jsonpointer==3.0.0
jsonschema_rs==0.29.1
langchain-core==1.2.2
langgraph==1.0.5
langgraph-api==0.6.8
langgraph-checkpoint==3.0.1
langgraph-cli==0.4.11
langgraph-prebuilt==1.0.5
langgraph-runtime-inmem==0.20.1
langgraph-sdk==0.3.0
langsmith==0.5.0
opentelemetry-api==1.39.1
opentelemetry-exporter-otlp-proto-common==1.39.1
opentelemetry-exporter-otlp-proto-http==1.39.1
opentelemetry-proto==1.39.1
opentelemetry-sdk==1.39.1
opentelemetry-semantic-conventions==0.60b1
orjson==3.11.5
ormsgpack==1.12.1
packaging==25.0
protobuf==6.33.2
pycparser==2.23
pydantic==2.12.5
pydantic_core==2.41.5
PyJWT==2.10.1
python-dotenv==1.2.1
PyYAML==6.0.3
requests==2.32.5
requests-toolbelt==1.0.0
setuptools==80.9.0
sse-starlette==2.1.3
starlette==0.50.0
structlog==25.5.0
tenacity==9.1.2
truststore==0.10.4
typing-inspection==0.4.2
typing_extensions==4.15.0
urllib3==2.6.2
uuid_utils==0.12.0
uvicorn==0.38.0
watchfiles==1.1.1
xxhash==3.6.0
zipp==3.23.0
zstandard==0.25.0
1 Like
6

Thanks, that did the trick!

I also set allowed origins in my langgraph.json though not sure if this is needed:

"http": {
    "cors": {
      "allow_origins": [
        "https://smith.langchain.com",
        "https://eu.smith.langchain.com"
      ],
      "allow_methods": ["GET", "POST", "PUT", "DELETE", "OPTIONS"],
      "allow_headers": ["*"],
      "allow_credentials": true
    }
  }
1 Like