Running older models fails with Unknown model gpt-5.1 is used
Resolved 💬 2 comments Opened Apr 25, 2026 by condwanaland Closed Apr 25, 2026
💡 Likely answer: A maintainer (github-actions[bot], contributor)
responded on this thread — see the highlighted reply below.
What version of the IDE extension are you using?
26.422.30944
What subscription do you have?
API
Which IDE are you using?
VS Code
What platform is your computer?
macOS
What issue are you seeing?
I have a minimal /Users/cneilson/.codex/config.toml file that has
model = "gpt-5.1"When opening the codex extention in VS Code, the Output logs show the error
message="codex_models_manager::model_info: Unknown model gpt-5.1 is used. This will use fallback model metadata."
I observe the same behaviour using the CLI
This used to work fine in March, but haven't touched it since then.
What steps can reproduce the bug?
Use a config file with
model = "gpt-5.1"
In it, then check output logs
### What is the expected behavior?
GPT 5.1 should be used
### Additional information
I am authenticated via an API key, not via ChatGPT
2 Comments
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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gpt-5.1 is no longer supported for Codex. For a list of currently-supported models, refer to this documentation.