Error DB · database

Error establishing a database connection

Ben Johnson · last verified 2026-08-02

Also seen as: WordPress database error · Cannot connect to MySQL · Access denied for user

What it actually means

This message means your PHP code ran, got as far as connecting to the database, and was turned away. The web server is fine and PHP is fine; the failure is strictly between your application and MySQL.

There are only four things it can be, and they are worth checking in this order:

1. Wrong username or password
2. Wrong database hostname
3. The connection limit for your user is full
4. The database server itself is down or the database was deleted

On shared hosting, cause 2 is the most common and the most surprising, because the value is almost never localhost.

Why it happens

The hostname is set to localhost

Nearly every tutorial on the internet says localhost, because on a single-server setup that is correct. On shared hosting it usually is not — your database lives on a separate database server, and you must use the hostname your host assigned you, such as sql203.example-host.com.

If you copied wp-config.php from a local development machine, this is almost certainly your problem.

Credentials changed or were never right

Database passwords get rotated, or the site was migrated and the new database user was created with a different name. On most shared hosts the database name and username are prefixed with your account ID (u1234_wp), and it is easy to carry over the unprefixed name from a local copy.

You have run out of connections

Shared hosting caps concurrent MySQL connections per user — often to a handful. If your site opens connections faster than it closes them, or a long-running query holds them open, new requests are refused with Too many connections and WordPress reports it as this generic message.

This version of the error is intermittent: the site works, then does not, then does again. Intermittency is the tell.

The database was deleted or is still being created

On a newly provisioned account the database server may not have been assigned yet. If you created the account minutes ago, wait and retry before debugging anything else.

How to fix it

1. Verify the four values in wp-config.php

Open wp-config.php and check every value against your control panel — do not trust your memory of them:

define('DB_NAME',     'u1234_wordpress');
define('DB_USER',     'u1234_wpuser');
define('DB_PASSWORD', 'the-actual-password');
define('DB_HOST',     'sql203.example-host.com'); // NOT localhost

Watch for trailing spaces inside the quotes. They are invisible and they break authentication.

2. Test the connection independently of WordPress

Put this in a file, load it once, then delete it. It tells you whether the problem is your credentials or your application:

<?php
$host = 'sql203.example-host.com';
$user = 'u1234_wpuser';
$pass = 'the-actual-password';
$db   = 'u1234_wordpress';

$mysqli = @new mysqli($host, $user, $pass, $db);
if ($mysqli->connect_errno) {
    echo 'FAILED (' . $mysqli->connect_errno . '): ' . $mysqli->connect_error;
} else {
    echo 'Connected. MySQL ' . $mysqli->server_info;
}

Access denied means credentials. Unknown MySQL server host means the hostname. Too many connections means you are at your limit.

3. Confirm the database still exists and has tables

Open phpMyAdmin from your control panel and check that the database is listed and that it contains tables. An empty database connects successfully but produces a different failure mode — usually a redirect to the installer.

If the database is genuinely gone and you have no backup, the site’s content is gone with it. This is the single strongest argument for taking your own backups on any free plan.

4. Release stuck connections

If the error is intermittent and you suspect connection exhaustion, look for queries that never finish:

SHOW PROCESSLIST;

Anything in Sleep for a long time is a connection your application opened and never closed. In PHP, that usually means a missing $mysqli->close() in a long-running script, or a plugin opening its own second connection on every page load.

On CWP specifically

When this means you've outgrown free hosting

Related errors

• 508 508 Resource Limit Is Reached
  Your account hit its CPU, memory, or concurrent-process ceiling, so the server refused the request instead of letting your site destabilise the machine.
• 500 500 Internal Server Error
  Something in your application or server configuration crashed, and the server is deliberately withholding the detail from visitors — the real message is in your error log.
• 504 504 Gateway Timeout
  The proxy in front gave up waiting for the backend to answer — your code is running, it is just taking too long.
• 1040 MySQL: Too many connections
  Your account is already holding as many database connections as it's allowed, so new requests are refused until one frees up.
• WP WordPress login redirect loop
  You submit correct credentials, WordPress sends you back to the login page, and nothing tells you why.