Why Does PostgreSQL Show “FATAL: password authentication failed for user ‘postgres’” and How to Fix It?

PostgreSQL database connection error: psql: error: FATAL: password authentication failed for user “postgres”

Environment: CentOS 7.6 host jeven, IP 192.168.3.166, PostgreSQL 13.10 installed via yum.

1. PostgreSQL overview

PostgreSQL (Postgres) is an open‑source relational DBMS supporting transactions, concurrency, complex queries, extensions, and advanced features such as foreign keys, triggers, and stored procedures.

2. Error scenario

[root@jeven ~]# psql -h192.168.3.166 -Upostgres -W
Password:
psql: error: FATAL: password authentication failed for user "postgres"

3. Possible causes

Wrong password entered.

Incorrect settings in postgresql.conf.

Incorrect settings in pg_hba.conf.

Password not set correctly for the user.

4. Configuration checks

Verify listen_addresses = '*' in postgresql.conf.

Typical pg_hba.conf entries:

host all all 127.0.0.1/32 ident
host all all 0.0.0.0/0 md5

5. Solutions

5.1 Reset forgotten password

su - postgres
psql -c "ALTER USER postgres WITH PASSWORD 'postgres';"

5.2 Correct password setting

sudo -u postgres psql -c "ALTER USER postgres WITH PASSWORD 'postgres';"

5.3 Fix configuration files

Ensure listen_addresses and pg_hba.conf entries are correct, then restart PostgreSQL.

5.4 Temporary trust authentication

vim /var/lib/pgsql/13/data/pg_hba.conf
# change to:
host all all 127.0.0.1/32 trust
host all all 0.0.0.0/0 trust

5.5 Re‑install in a clean environment

If configuration issues persist, consider redeploying PostgreSQL on a fresh system.

6. Summary of common causes

Incorrect connection parameters (host, port, user, password).

Database service not started.

Insufficient user privileges.

Firewall or network blockage.

Misconfigured postgresql.conf or pg_hba.conf.

Client‑server version incompatibility.