GET /v1beta/models returns 200 OK, but generateContent returns HTTP 403 "Your project has been denied access"

Gemini API
1

Hi Gemini API Team,

I am experiencing an asymmetric gateway authorization issue on a free-tier Google AI Studio API key.

While querying the model catalog (GET /v1beta/models) authenticates successfully and returns a 200 OK with available models, calling generateContent (POST) on any of those listed models fails immediately with an HTTP 403 PERMISSION_DENIED error.

1. Diagnostic Findings

Request Method & Endpoint Response Code Result
GET /v1beta/models?key={KEY} 200 OK Successfully returns active models (gemini-2.5-flash, gemini-flash-latest, etc.)
POST /v1beta/models/gemini-flash-latest:generateContent?key={KEY} 403 PERMISSION_DENIED Returns project denial error
POST /v1beta/models/gemini-2.5-flash:generateContent?key={KEY} 403 PERMISSION_DENIED Returns project denial error

2. Exact Error Payload (HTTP 403)

JSON

{
  "error": {
    "code": 403,
    "message": "Your project has been denied access. Please contact support.",
    "status": "PERMISSION_DENIED"
  }
}

3. Minimal Reproducible Apps Script Code (Sanitized)

JavaScript

// 1. THIS WORKS (Returns 200 OK + Model Catalog JSON)
function testListModels() {
  const apiKey = "AQ.Ab8RN...[REDACTED_KEY]";
  const url = `https://generativelanguage.googleapis.com/v1beta/models?key=${apiKey}&pageSize=100`;
  
  const res = UrlFetchApp.fetch(url, { "method": "get", "muteHttpExceptions": true });
  Logger.log(`[LIST MODELS CODE] ${res.getResponseCode()}`); // Logs: 200
}

// 2. THIS FAILS (Returns 403 PERMISSION_DENIED)
function testGenerateContent() {
  const apiKey = "AQ.Ab8RN...[REDACTED_KEY]";
  const url = `https://generativelanguage.googleapis.com/v1beta/models/gemini-flash-latest:generateContent?key=${apiKey}`;

  const payload = {
    "contents": [{"parts": [{"text": "Hello, world!"}]}]
  };

  const options = {
    "method": "post",
    "contentType": "application/json",
    "payload": JSON.stringify(payload),
    "muteHttpExceptions": true
  };

  const res = UrlFetchApp.fetch(url, options);
  Logger.log(`[GENERATE CONTENT CODE] ${res.getResponseCode()}`); // Logs: 403
  Logger.log(`[RESPONSE BODY] ${res.getContentText()}`);
}

4. Questions for Engineering / Developer Support

  1. Gateway Restriction: Why would an API key successfully pass authentication for model discovery (models.list), but get blocked with "Your project has been denied access" on inference (generateContent)?

  2. Account Policy / Flags: Is there an automated security or age/identity verification check on unbilled projects that restricts content generation endpoints while leaving catalog listing active?

  3. Resolution: How can this project-level inference restriction be cleared for free-tier development?

2

Hello @Gary_01 ,

Getting a 403 API error response and / or seeing “Unavailable” next to your project in AI studio 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. Once age verification is configured, retry your request or create a new API key in Google AI Studio.

  4. 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.