GPT-5.5 has six days left in Codex. On October 14, 2026, OpenAI retires it from ChatGPT, ChatGPT Work and Codex on every plan, from free accounts up to Business, Enterprise and Edu. Five days later, on October 19, GitHub pulls it from Copilot as well, along with five other models.

The short answer for Codex is to switch to GPT-6.1 Sol, gpt-6.1-sol. If you only ever pick models from a dropdown, that's a two-second change. The people who need to act this week are the ones who wrote gpt-5.5 down somewhere: a config file, a profile, a CI job, a scheduled task. Those keep asking for a model that won't be there.

What's retiring, and where

OpenAI, October 14. GPT-5.5 leaves ChatGPT, ChatGPT Work and Codex on all plans, "including consumer, Business, Enterprise, and Edu plans." OpenAI posted this in the Codex changelog on September 14 and repeats it on the Codex Models page. It gives a date but no time of day.

GitHub Copilot, October 19. GitHub's changelog lists six models leaving "all GitHub Copilot experiences," which it spells out as Copilot Chat, inline edits, ask and agent modes, and code completions:

  • GPT-5.5, replaced by GPT-5.6 Sol
  • GPT-5.4, replaced by GPT-5.6 Sol
  • GPT-5.4 mini, replaced by GPT-5.6 Luna
  • GPT-5 mini, replaced by GPT-5.6 Luna
  • Gemini 3.7 Flash, replaced by Gemini 3.8 Flash
  • Grok 4.5, replaced by Grok 4.6

Those replacements are GitHub's own picks for Copilot. That's why the GPT-5.5 line says GPT-5.6 Sol here, not the GPT-6.1 Sol that OpenAI recommends for Codex.

GPT-5.5 isn't the first model to go this autumn. gpt-5.4 and gpt-5.4-mini left Codex for ChatGPT sign-ins on August 31, and GPT-5.3-Codex-Spark followed on September 14.

What to switch to

Switch to GPT-6.1 Sol, gpt-6.1-sol. The Codex Models page recommends it for complex coding and agentic work and says it offers "near-Astra performance for complex work at a lower cost than Astra." For focused, repeatable tasks, the same page points to Luna.

GPT-6.1 Sol is still rolling out, so check where your plan stands:

  • Plus, Pro and Business: it's in the launch rollout, in the desktop app and the CLI.
  • Enterprise and Edu: also in the rollout, but off by default until an admin enables it.
  • Free and Go: "not included at launch." On these plans the Models page says to choose GPT-6 Luna (gpt-6-luna) in the desktop app.

If GPT-6.1 Sol hasn't reached your account yet, use GPT-6 Sol (gpt-6-sol) for now. It's the replacement the Models page lists for paid plans.

Admins should note one line in OpenAI's workspace guidance: "changing a default doesn't grant model access." Enable GPT-6.1 Sol for the people who need it before you point a team default at it.

About the names. The September 15 @ChatGPT post said to switch to "GPT-5.6 Sol or GPT-6 Astra." The Models page, which OpenAI keeps updated, now recommends gpt-6.1-sol, so that's the one to follow for Codex.

What breaks if you pinned gpt-5.5

OpenAI's list of places to check is short and specific: "workspace defaults, saved model settings, managed configurations, custom agents, scheduled tasks, and scripts that select a model." For Codex, that comes down to these:

  • Your config.toml. The desktop app, the CLI and the IDE extension all read the same file. If it pins gpt-5.5, change the model line. OpenAI's own example is:
  • model = "gpt-6.1-sol"
  • Project config. Codex also reads .codex/config.toml inside trusted projects, and those values beat your personal file. A repo that pins gpt-5.5 will keep overriding your fix until someone changes it there.
  • Profiles. Profiles now live in their own files, named ~/.codex/profile-name.config.toml, and use the same top-level model key. Check each one. Since Codex 0.134.0, a [profiles.profile-name] table inside config.toml isn't read at all, so any profile still stored that way is already being ignored.
  • Scripts and CI. Anything that starts Codex with a model flag needs the new name. The forms OpenAI documents are codex --model gpt-6.1-sol, codex exec -m gpt-6.1-sol "Review the current changes", and the generic override codex --config model='"gpt-6.1-sol"'. Inside an interactive session, /model switches on the spot.
  • Custom agents and scheduled tasks. These carry their own model choice, so fixing your config file won't fix them.
  • Copilot model pickers. If you picked GPT-5.5 in Copilot Chat, choose another model before the 19th. GitHub's suggested replacement there is GPT-5.6 Sol. On Copilot Business and Enterprise, GitHub says the suggested replacements are turned on automatically under default model enablement. The exception is when an admin has switched off the global default or disabled the model. In that case, the replacements have to be enabled through their model policies in Copilot settings. GitHub says no action is needed to remove the old models once they're deprecated.

OpenAI hasn't said what happens after the 14th to a session that still asks for gpt-5.5, whether it errors out or falls back to another model. Better to update the setting before then than find out.

What stays the same

The API keeps GPT-5.5. Both the changelog and the Models page say the retirement "does not apply to the OpenAI API," and the Models page lists GPT-5.5 as remaining "available on the OpenAI API."

Codex keeps it too, for one group: people who sign in with an API key rather than a ChatGPT account. @OpenAIDevs put it directly: "GPT-5.5 will remain available via the OpenAI API Platform and in Codex sessions authenticated with an API key." That matters for automation. OpenAI's non-interactive docs show CI runs authenticating with CODEX_API_KEY, and the retirement doesn't touch API-key sessions. What it does touch is Codex with a ChatGPT sign-in, so a job that runs under someone's ChatGPT login is in scope.

What to do this week

  • Search for gpt-5.5 in your dotfiles, repos, CI configs and saved automations.
  • Switch config.toml and each profile file to gpt-6.1-sol. If it isn't available to you yet, use gpt-6-sol for now. On Free and Go, use gpt-6-luna in the desktop app.
  • Check project configs in shared repos, so an old pin in a repo doesn't override your change.
  • Point scripts, custom agents and scheduled tasks at gpt-6.1-sol wherever they name a model.
  • Admins: enable GPT-6.1 Sol first, then change the defaults. Confirm it's on for the people who need it, then update workspace defaults and managed configs.
  • Copilot users: move off GPT-5.5 before October 19, and check whether your org turned off default model enablement.
  • If you still need GPT-5.5 itself, it stays available on the API and in API-key sessions in Codex.