# Agent stalling and LLM response not returning anything

**URL:** <https://forum.langchain.com/t/agent-stalling-and-llm-response-not-returning-anything/3125>\
**Category:** OSS Product Help\
**Created:** [March 10, 2026, 9:08pm UTC](https://forum.langchain.com/t/agent-stalling-and-llm-response-not-returning-anything/3125 "2026-03-10T21:08:34Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Art](https://avatars.discourse-cdn.com/v4/letter/a/8797f3/32.png) [@Art](https://forum.langchain.com/u/Art)\
**Post date:** [March 10, 2026, 9:08pm UTC](https://forum.langchain.com/t/agent-stalling-and-llm-response-not-returning-anything/3125/1 "2026-03-10T21:08:34Z")

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I am currently using Langchain for the LLM instances for my agent, however sometimes whenever I run the agent, it does not return anything or takes too long and returns error. I am able to observe this on Langsmith and I just see it spinning. However, I am not really sure what is the cause of the issue. I am using Openrouter as my provider, however every time I call their API normally I am able to get a response all the time, so I am thinking this could be cause by Langchain. Does anyone have any experience with this and what they would recommend? Also, I am thinking of moving off of Langchain for the LLM instances and such, and use Langgrpah with the native APIs, would this be plausible?

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**Author:** ![pawel-twardziak](https://yyz1.discourse-cdn.com/flex007/user_avatar/forum.langchain.com/pawel-twardziak/32/960_2.png) [@pawel-twardziak](https://forum.langchain.com/u/pawel-twardziak)\
**Post date:** [March 10, 2026, 10:02pm UTC](https://forum.langchain.com/t/agent-stalling-and-llm-response-not-returning-anything/3125/2 "2026-03-10T22:02:26Z")

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hi @Art

how do you use OpenRouter through LangChain - via `ChatOpenAI` with a custom `base_url`, or via the dedicated `langchain-openrouter` package?

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<div class="post-metadata">

**Author:** ![Art](https://avatars.discourse-cdn.com/v4/letter/a/8797f3/32.png) [@Art](https://forum.langchain.com/u/Art)\
**Post date:** [March 10, 2026, 10:14pm UTC](https://forum.langchain.com/t/agent-stalling-and-llm-response-not-returning-anything/3125/3 "2026-03-10T22:14:38Z")

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HI @pawel-twardziak ,

Thanks for the quick response. I use it with the init\_chat\_model using the custom base url. I assume that this is using the ChatOpenAI under the hood to my understanding.

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<div class="post-metadata">

**Author:** ![pawel-twardziak](https://yyz1.discourse-cdn.com/flex007/user_avatar/forum.langchain.com/pawel-twardziak/32/960_2.png) [@pawel-twardziak](https://forum.langchain.com/u/pawel-twardziak)\
**Post date:** [March 10, 2026, 11:06pm UTC](https://forum.langchain.com/t/agent-stalling-and-llm-response-not-returning-anything/3125/4 "2026-03-10T23:06:14Z")

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hi @Art

When you call `init_chat_model` with a model name and a custom `base_url`, the function infers the provider from the model name prefix.

For example:

- `"gpt-4o"` → infers `"openai"` → creates `ChatOpenAI`
- `"claude-sonnet-4-5"` → infers `"anthropic"` → creates `ChatAnthropic`

So if you’re doing something like:

```python
from langchain.chat_models import init_chat_model

llm = init_chat_model(
    "gpt-4o",
    base_url="https://openrouter.ai/api/v1",
    api_key="your-openrouter-key",
)

```

This creates a `ChatOpenAI` instance with a custom `base_url` pointing to OpenRouter.

This setup has two critical default behaviors that cause stalling:

Problem 1: No default timeout - `ChatOpenAI` sets `request_timeout` to `None` by default

Problem 2: `stream_usage` stays disabled with custom `base_url` - when a custom `base_url` is set, `ChatOpenAI` skips enabling `stream_usage` by default

add explicit timeout and retries:

```python
from langchain.chat_models import init_chat_model

llm = init_chat_model(
    "gpt-4o",
    base_url="https://openrouter.ai/api/v1",
    api_key="your-openrouter-key",
    timeout=60,
    max_retries=2,
    stream_usage=True,
)

```

or better alternative imho (the package itself is quite old though):

`model_provider="openrouter"` instead of custom `base_url`

```python
from langchain.chat_models import init_chat_model

llm = init_chat_model(
    "openai/gpt-4o", 
    model_provider="openrouter",
    timeout=30000, 
    max_retries=1,
)

```

It requires `pip install langchain-openrouter`