AI Studio TTS returns HTTP 403 after prepaid activation; billing support confirmed no holds

Gemini API
1

Google AI Studio speech generation returns HTTP 403 from MakerSuiteService/GenerateContent with this response:

[,[7,"The caller does not have permission"]]

Test: gemini-2.5-flash-preview-tts, voice Alnilam, a short ordinary English sentence. No audio is produced. A prior test with another available TTS model also failed.

Verified:

  • Selected API key and AI Studio project URL match.
  • Gemini API (generativelanguage.googleapis.com) is enabled.
  • AI Studio-created authorization key is marked usable and bound to a service account.
  • API restriction is Gemini API; no application restriction.
  • Signed-in project owner has accepted paid-service terms.
  • Human Cloud Billing support confirmed the prepaid account is active and healthy, with no activation, payment, or verification holds.
  • Cloud dashboard showed no suspension banner.
  • Earlier project creation returned “The request is suspicious”; the owner subsequently created the project manually.

Billing support referred me here and could not diagnose the access denial. I have not removed key restrictions or created replacement keys as a workaround.

How can I identify the exact denied permission or request a private account/project access review? Please provide a secure support path for any project identifiers needed. I do not want to post credentials or personal account information publicly.

2

Helo @Jason_Lin ,

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)