404 This model is only supported in v1/responses and not in v1/chat/completions.

[ewitte12-ui]

I've not been able to get past this message. I've tried with and without useLegacyCompletionsEndpoint: true

Config.yaml

name: Local Config
version: 1.0.0
schema: v1
models:

• name: GPT-5.1 Codex
  provider: openai
  model: gpt-5.1-codex # exact model ID from your provider
  apiKey: REMOVED # same key you use in Open WebUI
  apiBase: https://api.openai.com/v1 # same API URL as in Open WebUI Connections, NO trailing slash
  roles:

  • chat
  • edit
  • apply

• name: GPT-5.1 Codex Mini
  provider: openai
  model: gpt-5.1-codex-mini # exact model ID from your provider
  apiKey: REMOVED
  apiBase: https://api.openai.com/v1
  roles:

  • chat
  • edit
  • apply

[ewitte12-ui]

This ended up being because the newer models required responses. I switched to the pre-release and was able to get them to work.