A generic connection-level error occurred. The client could not establish or maintain a session with the PostgreSQL server.
Common causes
1PostgreSQL server is not running or unreachable on the configured port
2Network firewall or security group blocks the connection
3Connection pool exhausted — too many concurrent connections
4Server crashed or was restarted mid-session
How to fix it
1Step 1: Verify the PostgreSQL server is running: `pg_isready -h <host> -p <port>`.
2Step 2: Check firewall rules and security groups to ensure port 5432 (or custom port) is open.
3Step 3: Review `pg_hba.conf` to confirm the client IP is allowed.
4Step 4: Check `max_connections` in `postgresql.conf` and compare with active connections via `SELECT count(*) FROM pg_stat_activity`.
5Step 5: Review PostgreSQL server logs (`/var/log/postgresql/`) for crash or OOM events.
Example log output
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) connection to server at "10.0.1.45" (10.0.1.45), port 5432 failed: FATAL: connection refused
Is the server running on that host and accepting TCP/IP connections?
dbt.exceptions.FailedToConnectError: Failed to connect to database: SQLSTATE 08000
Frequently asked questions
How do I prevent 08000 errors in automated pipelines?
Add retry logic with exponential backoff, validate data quality before loading, and monitor pipeline failures in MetricSign to catch this error early.
