Vertex AI
gemini-3.1-flash-lite-preview model retirement
Stopped workingSubscribe to Vertex AIShare
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 you get
What Vertex AI answers a call to gemini-3.1-flash-lite-preview once the model is gone, as recorded from real responses:
{"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 of gemini-3.1-flash-lite-preview
Consult the documentation to migrate your project to the latest Google models.
In 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
Facts
Questions
When does gemini-3.1-flash-lite-preview shut down?
Calls to the model gemini-3.1-flash-lite-preview on Vertex AI stopped working on July 9, 2026.
What happens to calls after July 9, 2026?
They have failed since July 9, 2026.
What error does gemini-3.1-flash-lite-preview return once it is shut down?
Vertex AI answers HTTP 404: "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.". Send another model to fix it.
When was gemini-3.1-flash-lite-preview released?
gemini-3.1-flash-lite-preview was released on March 3, 2026, according to models.dev.
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.
gemini-3.1-flash-lite-preview on other APIs 1
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Gemini API
gemini-3.1-flash-lite-previewModel 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.