Vertex AI
imagen-4.0-fast-generate-001 model retirement
Stopped workingSubscribe to Vertex AIShare
On June 30, 2026, the model imagen-4.0-fast-generate-001 was retired on Vertex AI. Calls to model imagen-4.0-fast-generate-001 fail since that day. This retirement was announced on March 24, 2026.
The error you get
What Vertex AI answers a call to imagen-4.0-fast-generate-001 once the model is gone, as recorded from real responses:
{"error":{"code":404,"message":"Publisher model `projects/{project}/locations/{region}/publishers/google/models/imagen-4.0-fast-generate-001` 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 of imagen-4.0-fast-generate-001
Update your model endpoints to gemini-2.5-flash-image to avoid service disruption.
In Vertex AI's words
| `imagen-4.0-fast-generate-001` | `gemini-2.5-flash-image` |
Facts
Questions
When does imagen-4.0-fast-generate-001 shut down?
Calls to the model imagen-4.0-fast-generate-001 on Vertex AI stopped working on June 30, 2026.
What happens to calls after June 30, 2026?
They have failed since June 30, 2026.
What error does imagen-4.0-fast-generate-001 return once it is shut down?
Vertex AI answers HTTP 404: "Publisher model `projects/{project}/locations/{region}/publishers/google/models/imagen-4.0-fast-generate-001` 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.". Send another model to fix it.
How do I find the calls this hits in my code?
Okapi reads your repository, finds the calls this change hits and opens a pull request with the fix. It never commits to your branches: every change comes as a pull request you review.
imagen-4.0-fast-generate-001 on other APIs 1
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Gemini API
imagen-4.0-fast-generate-001Model retirement Stopped working
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You fixed this one by hand.
Okapi opens the pull request with the fix before the next breaking change reaches your code.