OpenAI GPT-5.4: Unable to set reasoning effort = none with temperature = 0

Author: FeNoMeNaCreated Apr 24, 2026Updated May 22, 2026

Currently, when using OpenAI models such as gpt-5.4 via LangChainGo, it is not possible to configure a request with both:

temperature = 0 reasoning effort = none (via ThinkingModeNone)

According to the OpenAI documentation, this combination should be supported: https://developers.openai.com/api/docs/guides/latest-model#gpt-54-parameter-compatibility

However, the current implementation appears to reject or ignore this configuration.