Knowledge Base

WordPress websites do not work after migration: Error establishing a database connection

Symptoms

WordPress website is not accessible after migration with the following error:

Error establishing a database connection

Cause

Users’ database passwords are not correct on the source server.

Resolution

Use one of the following workarounds:

Set the correct database user password in the /var/www/vhost/example.com/httpdocs/wp-config.php file on the source server using Plesk File Manager or SSH connection and re-migrate the subscription.
If content re-syncing is not planned or is not possible, update the database password as follows:

Update the database password on the destination server

Log in to Plesk.
Go to Domains > example.com > File Manager and find the wp-config.php file in the domain directory.

Open wp-config.php and find the first lines defining the database, database user, database password and database server address, like the following:

/** The name of the database for WordPress /
 define('DB_NAME', 'dbname');
 /* MySQL database username /
 define('DB_USER', 'username');
 /* MySQL database password */
 define('DB_PASSWORD', 'password');
 /** MySQL hostname */ 
 define('DB_HOST', '203.0.113.2:3306');

Copy the password (without the '' symbols).
Go to Domains > example.com > Databases and click the database user username under the database dbname (see lines from wp-config.php from the previous step for reference).
Paste the password (see step 2) to the New password and Confirm password fields and click OK or Apply.

Note: In case an error is shown ‘Database user name is greater than 16 characters‘, shorten the user name to under 16 characters on the Database User page in Plesk, and then update the username in wp-config.php accordingly.
Ensure that DB_HOST is set to the hostname or IP address displayed in Domains > example.com > Databases