Hello Community,
I am facing a persistent and critical authentication error and have exhausted all possible troubleshooting steps. No Google service (Looker Studio, AppSheet) can connect to my Cloud SQL for PostgreSQL instance, even a brand new one. **Latest Test Performed (Total Reset):** 1. I deleted all previous instances. 2. I created a **brand new, clean PostgreSQL 14 instance** from scratch (`db-juridico-financeiro-prod`) in `southamerica-east1`. 3. Inside this new instance, I created a new database (`postgres`), all necessary tables, and a **brand new database user (`app_user`)** with a new, known-strong password. 4. I granted this new user all necessary privileges (`CONNECT`, `USAGE`, `DML`) on the database and tables via Cloud SQL Studio. 5. I confirmed that the **Cloud SQL Admin API is ENABLED**. 6. I confirmed that the **firewall (“Authorized Networks”) is open for testing (`0.0.0.0/0`)**. **Result:** I then tried to connect Looker Studio to this **brand new instance** using the **brand new user** and the correct JDBC URL (`jdbc:postgresql://google/postgres?..`). The connection **failed again** with a generic error code `3cd70dcd`. **Conclusion:** This definitively proves the issue is not related to a specific database user, a corrupted instance, a database version mismatch, a firewall misconfiguration, or a client-side credential error. The problem seems to be a platform-level issue within my Google Cloud project (PII Removed by Staff) that is blocking all external, password-based authentication attempts to Cloud SQL. This issue has persisted even after changing database providers (from Neon to Cloud SQL) and after creating a completely new and clean environment within GCP. Could an engineer please investigate the backend logs for this project to determine why all authentication attempts are being rejected by the platform?
Thank you.