# gpt-3.5-turbo-instruct

Calls to the model gpt-3.5-turbo-instruct on OpenAI stopped working on September 28, 2026.

Calls to model gpt-3.5-turbo-instruct fail since September 28, 2026. OpenAI shut down the model on that date, and requests using this model ID are no longer served.

## The error OpenAI returns once gpt-3.5-turbo-instruct is gone

HTTP 404

```json
{"error":{"message":"The model `gpt-3.5-turbo-instruct` has been deprecated, learn more here: https://platform.openai.com/docs/deprecations","type":"invalid_request_error","param":null,"code":"model_not_found"}}
```

## What to use instead

Move to gpt-5.6-terra, recommended by OpenAI. Because gpt-5.6-terra is not served on /v1/completions, moving requires more than changing an ID: update calls to Chat Completions (/v1/chat/completions) or the Responses API (/v1/responses), convert the prompt string to messages or input, and extract text from the returned message rather than choices[].text.

gpt-5.6-terra is not served on /v1/completions. Move the call to Chat Completions (/v1/chat/completions) or the Responses API (/v1/responses): the prompt string becomes messages or input, and the text comes back in a message rather than choices[].text.

- API: OpenAI (api.openai.com)
- Model: gpt-3.5-turbo-instruct
- Released: September 20, 2023 (models.dev)
- Kind: Model retirement
- Takes effect: September 28, 2026
- Calls after that day: fail
- Calls it hits: `model gpt-3.5-turbo-instruct`
- Source: [Deprecations page](https://developers.openai.com/api/docs/deprecations)
- Verified: November 6, 2026, against OpenAI's own pages
- Page: https://www.okapi.bot/models/openai/gpt-3.5-turbo-instruct/

## OpenAI's words

> Shutdown date: 2026-09-28; Model / system: gpt-3.5-turbo-instruct; Recommended replacement: gpt-5.6-terra

Okapi finds the calls this change hits in your repo and opens the pull request with the fix: https://github.com/apps/okapi-agent