postgresql connection failed - PostgreSQL connection failed or authentication error

root@linuxfix:~/postgresql_connection_failed$

postgresql connection failed

PostgreSQL connection failed or authentication error

Solutions

Prerequisites: Start by updating your system to resolve common issues and ensure the solutions provided below are compatible with your current environment.

check_latest_version && sudo apt update && sudo apt upgrade -y

Check PostgreSQL service

Verify service status:

sudo systemctl status postgresql

sudo -u postgres psql -c "SELECT version();"

ps aux | grep postgres

Test authentication

Try different auth methods:

sudo -u postgres psql

psql -U username -d database -h localhost

psql -l

Check configuration

Verify PostgreSQL config:

sudo cat /etc/postgresql/*/main/pg_hba.conf

sudo cat /etc/postgresql/*/main/postgresql.conf

What is postgresql connection failed?

PostgreSQL server unreachable, authentication failed, or database does not exist.

Common scenarios: Wrong credentials, service down, authentication method issues, or database missing.

Common Causes

Wrong username/password
Database does not exist
PostgreSQL service down
Authentication method mismatch
Connection limit reached

Debugging Tips

tail -f /var/log/postgresql/postgresql-*.log

netstat -tlnp | grep 5432

sudo -u postgres psql -c "SELECT * FROM pg_stat_activity;"

Prevention

Document database credentials
Monitor PostgreSQL logs
Regular connection testing

Additional Resources

PostgreSQL Manual

PostgreSQL administration guide

postgresql database authentication connection