Subject: Getting 404 Not Found for Imagen model on Vertex AI, despite having a quota

Hello everyone,

I’m trying to use Imagen on Vertex AI for image generation, but I’ve run into a confusing issue and am hoping someone in the community can offer some insight.

Goal:
I want to generate an image using the vertexai Python library, calling the imagen-3.0-fast-generate model in the us-central1 region.

The Problem:
On my Google Cloud Console “Quotas” page, I can clearly see that I have a quota of “20 requests per minute” for the Vertex AI API with the following dimensions:

  • Service: Vertex AI API
  • Region: us-central1
  • Model (base_model): imagen-3.0-fast-generate
  • Quota: 20 / minute

However, when my Python script calls the API with this exact configuration, it doesn’t return a quota error (429), but instead returns a 404 Not Found error:

404 Publisher Model `projects/(PII Removed by User)/locations/us-central1/publishers/google/models/imagen-3.0-fast-generate` not found.

This seems to be a contradiction: the quota exists, but the API claims the model can’t be found.

What I’ve Tried So Far:

  • Double-checked that the Project ID, model name, and region string are all correct.
  • Confirmed the Vertex AI API is enabled and a valid billing account is linked to the project.
  • To isolate the problem, I created a brand new Google Cloud project and repeated the entire setup process from scratch, but the exact same 404 error occurs.
  • Created a new service account in the new project and granted it the “Vertex AI User” role.
  • Confirmed the GOOGLE_APPLICATION_CREDENTIALS environment variable is set correctly.
  • Tried other model/region combinations that also showed a valid quota, but they all resulted in similar errors.

My Questions:

  1. Has anyone else experienced this kind of discrepancy between the Quota page and the actual API response for Vertex AI models?
  2. Is it possible this is a known issue or a temporary problem on the Google Cloud side?
  3. Is there a step I might be missing to get the quota properly recognized by the Vertex AI API?

Any help or suggestions would be greatly appreciated. Thank you!

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Hello @イェ_ガ_エレン ,

Looking at the Imagen 3 Fast Generation Documentation, it seems that the correct Model ID is: imagen-3.0-fast-generate-001

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