Gemini image input returns 403 while text works — project access check

Gemini API
1

Hello,

I am troubleshooting Gemini API multimodal access on this Google Cloud project:

Project ID:
gen-lang-client-06437250..

Model:
gemini-3.6-flash

Current behavior:

  • Gemini API is enabled.
  • The API key is active and restricted to Gemini API.
  • The project has available free-tier quota.
  • A simple text generation request succeeds.
  • DNS, HTTPS and SDK connectivity are working.
  • 2-Step Verification and account recovery information are configured.

However, when I send a very small synthetic PNG image with a simple Vision request, Gemini returns:

403 PERMISSION_DENIED
“Your project has been denied access. Please contact support.”

The test image contains only synthetic text and shapes, so this is not related to private or copyrighted content.

Since text requests succeed with the same key and model, could someone please check whether multimodal access for this project is restricted or flagged?

I can provide sanitized request/error details if needed.

Thank you.