Fix WordPress "Error Establishing a Database Connection"

This WordPress error means it couldn't reach its database. The cause is almost always the credentials in wp-config.php, the database being down, corrupted tables, or the database hitting its connection limit. Here is how to fix each.

Cause 1: wrong credentials in wp-config.php

After a migration or password change, the details in wp-config.php stop matching the database. Confirm all four:

define('DB_NAME', 'your_db');
define('DB_USER', 'your_user');
define('DB_PASSWORD', 'your_password');
define('DB_HOST', 'localhost');   // sometimes 127.0.0.1

If the login itself is denied, see MySQL access denied (1045).

Cause 2: the database server is down

If MySQL/MariaDB isn't running, every site on it shows this error. Restart it and check why it stopped — see MySQL/MariaDB won't start:

systemctl status mariadb && systemctl restart mariadb

Cause 3: corrupted database tables

A crash can corrupt tables. WordPress has a built-in repair tool — enable it temporarily in wp-config.php, run it, then remove the line:

define('WP_ALLOW_REPAIR', true);
// then visit /wp-admin/maint/repair.php

Check wp-config credentials first, confirm the DB server is running, then repair tables if needed. One site = config; all sites = the DB server.

Cause 4: too many database connections

On a busy site, MySQL/MariaDB has a maximum connection limit. Once it's hit, new connections — including yours — are refused and WordPress shows this same error. See MySQL too many connections to raise the limit or find what's exhausting it.

Cause 5: the database server is on a different host

On some setups the database runs on a separate server. If DB_HOST points to an internal IP or hostname that changed — after a migration, a new VPS, or a firewall rule — WordPress can't reach it even though the database itself is healthy. Confirm DB_HOST is reachable from the web server.

How to prevent this error

• Back up wp-config.php and your database before any migration.
• Keep database credentials in a password manager so a rotation doesn't break the site.
• Monitor MySQL/MariaDB uptime.
• Set a sane max_connections for your traffic so one spike doesn't lock everyone out.

Related errors

If the site loads but shows a blank page instead of this error, see the white screen of death guide. Migrating to a new server? See how to migrate a WordPress site so the credentials carry over cleanly.

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