Wrong password or username in the connection string or linked service. `pg_hba.conf` does not allow the connection method (e.g., md5 required but peer used). User account was dropped or password was rotated without updating the pipeline. SSL certificate or GSSAPI authentication failure

Step 1: Verify the username and password in the connection string.. Step 2: Check `pg_hba.conf` to confirm the client's IP and auth method are allowed.. Step 3: Test connectivity: `psql -h -U -d `.. Step 4: If the password was rotated, update credentials in all linked services and secret stores.. Step 5: Review PostgreSQL server logs for the specific authentication failure reason.

Critical severitypermissions

PostgreSQL Error:
28000

What does this error mean?

Authentication failed — the provided username, password, or authentication method is not accepted by the PostgreSQL server.

Common causes

1Wrong password or username in the connection string or linked service
2`pg_hba.conf` does not allow the connection method (e.g., md5 required but peer used)
3User account was dropped or password was rotated without updating the pipeline
4SSL certificate or GSSAPI authentication failure

How to fix it

1Step 1: Verify the username and password in the connection string.
2Step 2: Check `pg_hba.conf` to confirm the client's IP and auth method are allowed.
3Step 3: Test connectivity: `psql -h <host> -U <user> -d <db>`.
4Step 4: If the password was rotated, update credentials in all linked services and secret stores.
5Step 5: Review PostgreSQL server logs for the specific authentication failure reason.

Example log output

FATAL: password authentication failed for user "etl_user"
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) FATAL: password authentication failed for user "etl_user"
Task exited with return code 1 after 3 attempts — marking pipeline run as Failed.

Frequently asked questions

How do I prevent 28000 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.

Source · www.postgresql.org/docs/current/errcodes-appendix.html