On October 14, 2026, OpenAI retires GPT-5.5 from ChatGPT, ChatGPT Work and Codex. If anything in your setup depends on it, here's what to expect, how to find those dependencies, and your options for keeping things running: migrate to a newer model, or keep GPT-5.5 through the API.
What's changing
| Where | What happens on October 14 |
|---|---|
| ChatGPT, ChatGPT Work, and Codex signed in with ChatGPT | GPT-5.5 is gone, on every plan: consumer, Business, Enterprise and Edu |
| The OpenAI API | Not affected. gpt-5.5 stays available |
| OpenAI's official replacement | GPT-5.6 Sol (gpt-5.6-sol) |
Sol or Terra?
OpenAI's migration guidance says to switch to Sol. Its own model guide also says Terra is "a natural starting point for work you previously gave GPT-5.5," with performance competitive with GPT-5.5 at a lower cost.
| Pick | When |
|---|---|
| GPT-5.6 Sol | You used GPT-5.5 for hard, open-ended work: complex code changes, deep research, polished documents |
| GPT-5.6 Terra | You used it as your everyday default and want similar results for less usage |
| GPT-6 Astra | The hardest multi-step work across code, apps and research, where your plan includes it |
Also note: GPT-5.5's reasoning effort levels don't map exactly to GPT-5.6. OpenAI suggests trying a familiar task at a lower setting first, then adjusting.
Where gpt-5.5 hides
Changing the model in the picker isn't enough if you set it anywhere else. OpenAI lists these places:
- Workspace defaults
- Saved model settings
- Your
config.toml(model = "gpt-5.5") - Custom agents
- Scheduled tasks
- Scripts and commands that select a model, like
codex exec --model gpt-5.5
To find hardcoded references in your config and current project:
grep -rn "gpt-5\.5" ~/.codex/config.toml . 2>/dev/null
Admins: changing a workspace default doesn't grant access to the new model. Confirm the replacement is available to each affected user and client.
Test before the deadline
Don't find out on October 15 that a scheduled task now behaves differently. Pick three tasks you run often, then:
Here's a task I used to run on GPT-5.5: [task + example output]. Do it again. Then tell me what you did differently from that example and what I should change in my prompt to get the result I expect.
Run it on Sol and Terra at a lower effort than you used before. Keep whichever meets your bar at the lower cost.
Pros and cons
| Pros | Cons |
|---|---|
| Newer models, and Terra may match your GPT-5.5 work at a lower cost | Hardcoded settings and scheduled tasks can break or shift quietly |
| A simpler lineup: Astra, Sol, Terra and Luna | Prompts tuned for GPT-5.5 may behave differently |
| The API keeps GPT-5.5 if you truly depend on it | Staying on it through the API means paying per token instead of using your plan |
The bigger lesson
GPT-5.5 launched in April and leaves ChatGPT and Codex in October. GPT-5.4 left Codex on August 31, and GPT-5.2 and GPT-5.3-Codex were deprecated before that. Model retirements are now a regular event, not a rare one.
- Set the model in one place. Use a single
config.tomlline or one default, not a model name scattered across scripts and agents. - Test with tasks, not vibes. Keep a few saved tasks with known-good outputs, so every switch takes minutes.
- Keep your system bigger than any model. Your context, skills and workflows should outlast the model underneath. Rebuild your AI system so any tool or model can plug in.
Before October 14
- Search for
gpt-5.5and replace it everywhere - Test three real tasks on Sol and Terra
- Update scheduled tasks and custom agents
- Workspace admins: confirm access to the replacement
- Only if you truly need GPT-5.5: plan for API access and its costs
Go deeper: OpenAI's Codex models page · Claude Code vs Codex · Stop Building Your AI System Inside One Tool