[Solved] You wrote this callback handler but streaming output is not showing:class MyHandler(BaseCallbackHandler): def on_llm_new_token(self, token): print(token)What is the likely issue? | LangChain

LangChain - Production Deployment

You wrote this callback handler but streaming output is not showing:

class MyHandler(BaseCallbackHandler):
    def on_llm_new_token(self, token):
        print(token)

What is the likely issue?

ACallback class must inherit from StreamingCallbackHandler.

BMissing **kwargs parameter in on_llm_new_token method.

Cprint() cannot be used inside callbacks.

Dstreaming=True must be set inside the callback class.

Step-by-Step Solution

Solution:

Step 1: Check method signature requirements
on_llm_new_token requires token and **kwargs parameters.
Step 2: Identify missing **kwargs
Missing **kwargs causes method not to match expected signature, so callback is ignored.
Final Answer:
Missing **kwargs parameter in on_llm_new_token method. -> Option B
Quick Check:
Callback methods need correct parameters [OK]

Quick Trick: Include **kwargs in callback methods to avoid signature errors [OK]

Common Mistakes:

MISTAKES

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