How to Fix Langchain Hub Pull Error

When trying to run your first agent (https://js.langchain.com/docs/integrations/tools/tavily_search#usage) in Langchain, you will probably run into the following error:

The problem is that Hub Pull returns false. That is this part of the code:

const prompt = await pull<ChatPromptTemplate>(
  "hwchase17/openai-functions-agent"
);

To solve the problem, remove the code above and define a different prompt with a MessagesPlaceholder of "agent_scratchpad" like so:

 const prompt = ChatPromptTemplate.fromMessages([
  new MessagesPlaceholder("agent_scratchpad"),
  ["user", "{input}"],
  ["user", "Answer the question in detail and state your source."],
 ]);

The text ("Answer the question in detail and state your source.") can be any instructions you want.

This fixed mine.

You can find more tutorials on my YouTube channel (https://www.youtube.com/@njokusamsonebere2589) where I teach JavaScript and AI extensively.