[Solved] You wrote this code but no tracing data appears in LangSmith dashboard. What is the likely error? from langchain.llms import OpenAI from langchain.... | LangChain

LangChain - LangSmith Observability

You wrote this code but no tracing data appears in LangSmith dashboard. What is the likely error?

from langchain.llms import OpenAI
from langchain.callbacks import LangSmithTracer
tracer = LangSmithTracer()
llm = OpenAI()
llm('Hello', callbacks=[tracer])

AYou must call tracer.start() before using it.

BCallbacks should be passed when creating the LLM, not during the call.

CThe OpenAI class does not support callbacks at all.

DLangSmithTracer must be imported from langchain.tracing, not callbacks.

Step-by-Step Solution

Solution:

Step 1: Check how callbacks are passed to LLM
Callbacks should be set when creating the LLM instance, not during the call method.
Step 2: Identify the error in code usage
Passing callbacks in llm('Hello', callbacks=[tracer]) is ignored; correct usage is llm = OpenAI(callbacks=[tracer]).
Final Answer:
Callbacks should be passed when creating the LLM, not during the call. -> Option B
Quick Check:
Callbacks location matters = Callbacks should be passed when creating the LLM, not during the call. [OK]

Quick Trick: Pass callbacks when creating LLM instance [OK]

Common Mistakes:

MISTAKES

Passing callbacks in the call method instead of constructor
Importing tracer from wrong module
Expecting to manually start tracer

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You wrote this code but no tracing data appears in LangSmith dashboard. What is the likely error?

Step 1: Check how callbacks are passed to LLM

Step 2: Identify the error in code usage

Final Answer:

Quick Check:

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