403 permission denied for both speech and text in paid Gemini API project

Gemini API
1

Hi Gemini API team,

On September 19, 2026, Google AI Studio returned HTTP 403 / permission denied for Gemini 3.1 Flash TTS Preview. A separate minimal text-only prompt (“Reply with exactly: OK”) using Gemini 3.5 Flash Lite also failed with “Failed to generate content: permission denied.” Both requests used the same selected paid API key in a Tier 1 Prepay project.

I verified that the project has prepaid credit available, the Gemini API is enabled, the selected authorization key is marked Available and restricted to the Gemini API, and its bound service account is enabled. I found no project access warning in Cloud Console.

Could a Google team member identify the access condition denying generation and the appropriate recovery process? I can provide the project ID privately through an official support channel if needed.

2

Hello @WagnerReports

Getting a 403 API error response and / or seeing “Unavailable” next to your project in AI audio indicates a flag has been placed on your account. To proceed:

If you’re on the free tier with no billing attached, please try the below steps:

  1. Check Model Availability & Rate Limits:

    • Ensure that the model you are requesting is available on your current plan. For example, not all models are available on the free tier. You can verify model availability, quotas, and limits on the AI Studio Rate Limit dashboard.

  2. Ensure you have completed age verification by navigating to Google Account Age Verification and verifying date of birth in Google Account Personal Info.

  3. Complete Phone Verification and turn on 2-Step Verification (2SV) on the Google Account associated with your project.

  4. Once age, phone and 2sv are configured, retry your request or create a new API key in Google AI Studio.

  5. If completing these steps still does not restore access (or if using a model requiring a paid tier), you might want to consider adding prepayment credits directly in Google AI Studio and/ or attaching a Google Cloud Billing account in the Google Cloud Console. Please note this will mean you lose your free tier quota.

If you are on a paid tier:

  1. Check for banners / error callouts in the AI Studio Projects page & the Billing page. Mostly these flags cause visible banners or other errors on these pages with concrete next steps / appeal links. You can also check the email address associated with your project for information on next steps.

  2. If your GCP project/ billing account is suspended, you must submit an appeal directly through the Google Cloud Console following the Project Suspension Guidelines (Help Center)