# imagen-4.0-ultra-generate-exp-05-20

Calls to the model imagen-4.0-ultra-generate-exp-05-20 on Vertex AI stopped working on July 7, 2025.

## The error Vertex AI returns once imagen-4.0-ultra-generate-exp-05-20 is gone

HTTP 404

```json
{"error":{"code":404,"message":"Publisher model `projects/{project}/locations/{region}/publishers/google/models/imagen-4.0-ultra-generate-exp-05-20` 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"}}
```

- API: Vertex AI (aiplatform.googleapis.com)
- Model: imagen-4.0-ultra-generate-exp-05-20
- Kind: Model retirement
- Announced: June 11, 2025
- Takes effect: July 7, 2025
- Calls after that day: fail
- Calls it hits: `model imagen-4.0-ultra-generate-exp-05-20`
- Source: [Changelog](https://docs.cloud.google.com/vertex-ai/docs/release-notes)
- Verified: November 6, 2026, against Vertex AI's own pages
- Page: https://www.okapi.bot/models/vertex-ai/imagen-4.0-ultra-generate-exp-05-20/

## Vertex AI's words

> To avoid service interruption, migrate from imagen-4.0-ultra-generate-exp-05-20 and imagen-4.0-generate-preview-05-20 before 2025-07-07.

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