OpenAI node error: "messages must be a non-empty array, got null" despite having inputs

[achamm]

@CuO think i can actually pin it now. , I researched into it more, n8ns v2 message a model targets openais newer Responses api, which sends the prompt in an input field, not a messages array. your custom gateway almost certainly only speaks the older chat/completions api, so it receives a body with no messages key and hands back exactly that, got null, so its not really your config. two ways round it, use the legacy openai node (1.4, it still hits chat/completions) if you can pick the node version, or the http request node straight to your gateways /chat/completions with the messages array. same v2 responses-api root cause as this solved thread