Server Error

How to Resolve "Error Establishing a Database Connection" on Apache/Nginx

What Causes "Error Establishing a Database Connection"?

This error means your web application (WordPress, Laravel, custom PHP, etc.) successfully received an HTTP request but could not open a socket to the database server. The three most common causes are: wrong database credentials in the config file, the MySQL/MariaDB service has crashed or stopped, or the database itself has a corrupted table that prevents connections from completing authentication.

Quick Diagnostic Table

Scenario	Cause	Fix
Error on all pages	MySQL service stopped	sudo systemctl restart mysql
Error after password change	Wrong DB credentials in config	Update wp-config.php / .env
Error on specific site only	Wrong DB_HOST or DB_NAME	Verify config file values
Error after server crash	Corrupted InnoDB tables	Run mysqlcheck --repair
Too many connections error	MySQL max_connections hit	Increase max_connections in my.cnf

How to Fix the Database Connection Error

Fix 1 — Verify Database Credentials

Open your config file and cross-check every value:

• WordPress: /var/www/html/wp-config.php — check DB_NAME, DB_USER, DB_PASSWORD, DB_HOST
• Laravel: .env file — check DB_HOST, DB_DATABASE, DB_USERNAME, DB_PASSWORD

DB_HOST is almost always localhost or 127.0.0.1 unless your DB is on a remote server.

Fix 2 — Check and Restart MySQL

1. Check status: sudo systemctl status mysql
2. If inactive: sudo systemctl start mysql
3. If it fails to start, check: sudo journalctl -u mysql -n 50

Fix 3 — Test the Connection via CLI

Run this command to test your credentials directly: mysql -u your_db_user -p -h localhost your_db_name. If this fails with "Access denied," your password is wrong. If it shows "Can't connect to server," MySQL is not running.

Fix 4 — Repair Corrupted Tables

Run the MySQL repair utility: sudo mysqlcheck --repair --all-databases -u root -p. This fixes InnoDB and MyISAM table corruption that commonly occurs after unclean server shutdowns.

Fix 5 — Check MySQL Error Log

Inspect /var/log/mysql/error.log for the root cause. Look for InnoDB corruption messages, out-of-disk-space errors, or authentication plugin failures. Address the specific error found.

Verification