Critical Tier 1 (Prepaid) Error: 404 Not Found for Gemini 1.5 Flash on both v1 and v1beta

Project ID: [Gembot]

Billing Status: Prepaid (Tier 1) - $25.00 Balance Confirmed.

​Description of Issue:

My API calls are consistently failing with a 404 Not Found error when using a Tier 1 (Prepaid) API Key. This occurs despite having a confirmed balance and a correctly linked billing account.

​Tested Endpoints & Models:

​Models: gemini-1.5-flash, gemini-1.5-flash-latest, gemini-flash-latest.

​API Versions Tested:

https://generativelanguage.googleapis.com/v1/ (Failed with 404)

https://generativelanguage.googleapis.com/v1beta/ (Failed with 404)

​Authentication Methods: Tested via URL parameter (?key=) and Header (X-goog-api-key).

​Key Comparison:

​Free Tier Key: Works perfectly using the exact same code and endpoints.

​Tier 1 (Prepaid) Key: Returns: “message”: “models/gemini-1.5-flash is not found for API version v1, or is not supported for generateContent.”

​Troubleshooting Steps Taken:

​Verified that the project is in “Pay-as-you-go” mode in AI Studio.

​Confirmed the API Key is active and restricted to the correct project.

​Forced the use of the production v1 endpoint to rule out beta-only issues, with no success.

​Requested Action:

Please synchronize my Tier 1 quota across your production clusters. It appears that the billing status is not being propagated to the API Gateway, preventing access to production-grade models for this paid account.