How to Fix “Error Establishing a Database Connection” in WordPress

How to Fix “Error Establishing a Database Connection” in WordPress

“Error establishing a database connection” means WordPress loaded, tried to connect to its MySQL or MariaDB database, and failed. Every page needs the database, so the whole site shows that one white page. The cause is almost always one of five things: wrong credentials in wp-config.php, a database server that is down, a wrong database host, a corrupted database, or a server that ran out of memory or connections. This guide walks through them in the order that finds the problem fastest.

Quick answer: open wp-config.php and check DB_NAME, DB_USER, DB_PASSWORD and DB_HOST against your hosting dashboard. If they’re right, check that the database server is running and has free memory and disk space.

First: Is It the Front End, the Admin, or Both?

Open your site and then /wp-admin:

• Both show the error: WordPress can’t reach the database at all. Start with Step 1.

• The admin shows “One or more database tables are unavailable. The database may need to be repaired.” The connection works but tables are damaged. Go to Step 4.

• It comes and goes: the database server is overloaded or restarting. Go to Step 5.

Step 1: Check the Credentials in wp-config.php

WordPress reads its database settings from wp-config.php in the site root. Open it with your file manager or SFTP and find these four lines:

define( 'DB_NAME', 'database_name' );
define( 'DB_USER', 'database_user' );
define( 'DB_PASSWORD', 'password' );
define( 'DB_HOST', 'localhost' );

Compare each value with the database details in your hosting dashboard. Common mistakes:

• A password changed in the dashboard but not in wp-config.php (or the other way round).

• A database or user name missing a prefix your host adds, such as account_wpdb.

• A stray space or quote inside the value after a copy and paste.

• After a migration, the old host’s values still in the file.

You can test the credentials directly from SSH or a terminal:

mysql -u database_user -p -h localhost database_name

If that fails with “Access denied”, the user, password or host is wrong, or the user has no rights on that database. Reset the password in your dashboard and update wp-config.php.

Step 2: Check DB_HOST

localhost is correct when the database runs on the same server as WordPress. Many setups use something else:

• A separate database server or managed database: its hostname or IP, sometimes with a port, such as db.example.com:3306.

• Docker or Compose: the database service name, such as db, not localhost.

• A socket path on some servers: localhost:/var/run/mysqld/mysqld.sock.

If you moved hosts recently, this is the most likely culprit. Our guide to moving WordPress to a new host covers updating it.

Step 3: Check the Database Server Is Running

If the credentials are right, the database may simply be down. On a VPS:

sudo systemctl status mysql     # or: mariadb
sudo systemctl restart mysql
sudo journalctl -u mysql --since "1 hour ago"

Look for the reason it stopped. Two causes come up again and again:

• Out of memory: run dmesg -T | grep -i "killed process". If you see mysqld, the kernel’s out-of-memory killer stopped it. You need more RAM, a smaller innodb_buffer_pool_size, or fewer PHP workers competing for memory.

• Disk full: run df -h. MySQL can’t start or write when the disk is full; old logs and backups are the usual suspects.

On managed hosting you can’t restart MySQL yourself, so contact support with the time the error started.

Step 4: Repair a Corrupted Database

If the admin says tables need repair, WordPress has a built-in repair tool. Add this line to wp-config.php above “That’s all, stop editing!”:

define( 'WP_ALLOW_REPAIR', true );

Then visit https://yoursite.com/wp-admin/maint/repair.php and click “Repair Database”. This page works without logging in, so remove the line again as soon as you’re done.

With WP-CLI you can do the same from the command line:

wp db check
wp db repair

Take a backup first (wp db export) if the database still responds.

Step 5: The Error Comes and Goes (Too Many Connections or an Overloaded Server)

An intermittent error usually means the database is reachable but overwhelmed:

• Too many connections: MySQL’s max_connections limit was hit, often during a traffic spike or a bot attack on wp-login.php or xmlrpc.php.

• Slow queries piling up: a plugin running heavy queries on every page view.

• Not enough RAM: MySQL being restarted repeatedly by the out-of-memory killer.

Check the MySQL error log and your access log for the time of the errors. Blocking abusive bots, adding page caching and moving to a plan with more RAM fix most cases.

Step 6: Check the Site URL After a Migration

If only some pages fail after a move, check that siteurl and home in the wp_options table match your new domain, and that the table prefix in wp-config.php ($table_prefix) matches the tables in the database. A wrong prefix makes WordPress think it isn’t installed.

How to Stop It Happening Again

• Keep database credentials in one place and update wp-config.php whenever you change them.

• Watch RAM and disk space; most “random” database errors are a server out of one or the other.

• Keep daily backups you can restore with one click, so a corrupted database is a five-minute fix.

• Remove plugins you don’t use; each one can add queries.

Frequently Asked Questions

What causes “Error establishing a database connection” in WordPress?
WordPress can’t connect to its database. The usual causes are wrong credentials in wp-config.php, a wrong DB_HOST, a stopped or crashed MySQL server, a corrupted database, or a server out of memory or connections.

Will I lose my content?
Usually not. The posts and pages are still in the database; WordPress just can’t reach them. Only real corruption or a deleted database puts content at risk, which is why backups matter.

Why does it happen only sometimes?
An intermittent error points to an overloaded database: too many connections at once, slow queries or MySQL being restarted when the server runs out of RAM.

Is it safe to leave WP_ALLOW_REPAIR on?
No. The repair page doesn’t require a login while it’s enabled. Remove the line from wp-config.php as soon as the repair finishes.

How do I fix it after moving WordPress to a new host?
Update DB_NAME, DB_USER, DB_PASSWORD and DB_HOST in wp-config.php to the new host’s values, make sure the database was imported, and check that the table prefix matches.

Get Help With WordPress Databases

On RackUp Cloud WordPress hosting each site runs in its own container with reserved RAM, automated daily offsite backups and one-click rollback, so a broken database is a restore away. If you’re moving from another host, our team migrates WordPress sites for free. Plans start at $2.49 a month. See plans.