Azure OpenAI: maxTokens Error and Reasoning Summary Extraction I’m experiencing issues with Azure OpenAI using LangChain’s AzureChatOpenAI class and wanted to share my findings. The Problem When using AzureChatOpenAI with GPT-5, I’m getting this error: 400 Unsupported parameter: ‘maxTokens’ is no…

Hi @Nikfury have you tried this: import { AzureChatOpenAI } from "@langchain/openai"; const llm = new AzureChatOpenAI({ azureOpenAIApiKey: process.env.INTERNAL_AZURE_OPENAI_API_KEY, azureOpenAIApiInstanceName: "resource-name", azureOpenAIApiDeploymentName: "gpt-5", azureOpenAIApiVersion: …

Thanks @pawel-twardziak for responding again! I tested this exact code with my Azure OpenAI gpt-5 deployment and here are the results: Your suggested code fails with 404 error: const llm = new AzureChatOpenAI({ azureOpenAIApiKey: process.env.INTERNAL_AZURE_OPENAI_API_KEY, azureOpenAIA…

Hi @Nikfury try this: const ai = await llm.invoke(messages, { reasoning: { effort: "high", summary: "auto" /* summary config if desired */, }, }); Your issue might be related to that How to extract GPT-5 reasoning summaries with @langchain/openai? - #15 by pawel-twardziak …

If you are still getting 404, that is another issue which you might need to debug.

Hi @Nikfury bullets 1. and 2. should be sufficient. If it’s still not working for AzureChatOpenAI … then I don’t actually knowy why. Have you tried with ChatOpenAI from langchain? It should work following that How to extract GPT-5 reasoning summaries with @langchain/openai? - #14 by AMuresan

Unable to pass maxTokens and extract Resoning Summary in AzureChatOpenAI

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pawel-twardziak October 17, 2025, 6:20pm 6

Likely the 404 error is triggered by the source error. See that How to extract GPT-5 reasoning summaries with @langchain/openai? - #2 by pawel-twardziak

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Unable to pass maxTokens and extract Resoning Summary in AzureChatOpenAI

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