# gemini-3.1-flash-lite-preview

Calls to the model gemini-3.1-flash-lite-preview on Vertex AI stopped working on July 9, 2026.

Calls to model gemini-3.1-flash-lite-preview fail since July 9, 2026. On that date, Vertex AI retired the preview model endpoint, making it no longer accessible.

## The error Vertex AI returns once gemini-3.1-flash-lite-preview is gone

HTTP 404

```json
{"error":{"code":404,"message":"Publisher model `projects/{project}/locations/{region}/publishers/google/models/gemini-3.1-flash-lite-preview` was not found or your project does not have access to it. Ensure you are using a valid model name and that the model is available in the specified region.","status":"NOT_FOUND"}}
```

## What to use instead

Consult the documentation to migrate your project to the latest Google models.

- API: Vertex AI (aiplatform.googleapis.com)
- Model: gemini-3.1-flash-lite-preview
- Released: March 3, 2026 (models.dev)
- Kind: Model retirement
- Announced: July 9, 2026
- Takes effect: July 9, 2026
- Calls after that day: fail
- Calls it hits: `model gemini-3.1-flash-lite-preview`
- Source: [Changelog](https://docs.cloud.google.com/gemini-enterprise-agent-platform/release-notes)
- Verified: November 6, 2026, against Vertex AI's own pages
- Page: https://www.okapi.bot/models/vertex-ai/gemini-3.1-flash-lite-preview/

## Vertex AI's words

> The following preview model endpoints have been retired and are no longer accessible:
> 
> - gemini-2.5-flash-lite-preview-09-2025
> - gemini-2.5-flash-preview-05-2025
> - gemini-3.1-flash-lite-preview

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