How to switch Codex model settings to GPT-6.1 Sol after the GPT-5.5 retirement

GPT-5.5 has retired from Codex, effective October 14, 2026 at noon PDT (19:00 UTC). It applies to Codex signed in with ChatGPT; the OpenAI API and Codex sessions authenticated with an API key aren't affected.

The replacement depends on your plan. On Plus, Pro, Business, Enterprise and Edu, choose GPT-6.1 Sol (gpt-6.1-sol). On Free and Go, choose GPT-6 Luna (gpt-6-luna) in the desktop app.

If your config file still names gpt-5.5, change it. The desktop app, CLI and IDE extension all read the same file.

# ~/.codex/config.toml
model = "gpt-6.1-sol"

Remove the model line and Codex uses a recommended model.

Also find scripts and scheduled tasks that hard-code the model name.

grep -rn "gpt-5.5" ~/.codex ./scripts
codex exec --model gpt-6.1-sol "run the tests and summarize why they fail"

OpenAI lists workspace defaults, saved model settings, managed configurations, custom agents, scheduled tasks and scripts as places to check. Workspace admins should read the retirement section of the workspace model availability page.