postgres-errors-connection-auth

Quick Reference :

PostgreSQL rejects a client in two distinct phases. First the server checks pg_hba.conf (Host-Based Authentication): it scans records top-down and the first match wins on connection type, client address, database, and user. No match means no pg_hba.conf entry for host .... Second, the chosen method runs: scram-sha-256, md5, peer, cert, etc. A failed password gives password authentication failed for user ... (SQLSTATE 28P01). A connection that gets past auth can still be refused when the server is full: too many clients already / remaining connection slots are reserved ... (SQLSTATE 53300).