Error establishing a database connection: fix it

"Error Establishing a Database Connection" means your application couldn't connect to MySQL. The most common cause after a migration or fresh install is incorrect credentials in the configuration file. After that, check for database corruption and resource limits.

Wrong database credentials

For WordPress, open wp-config.php in File Manager and verify these four values match exactly what's configured in cPanel → MySQL Databases:

define( 'DB_NAME',     'username_dbname' );   // Full database name with prefix
define( 'DB_USER',     'username_dbuser' );   // Full database username with prefix
define( 'DB_PASSWORD', 'yourpassword' );     // Database user password
define( 'DB_HOST',     'localhost' );         // Always localhost on shared hosting

Common mistakes:

• Using the database name without the cPanel username prefix (e.g. mydb instead of cpanelusername_mydb)
• Using the wrong password (changed in cPanel but not updated in wp-config.php)
• Using a remote MySQL host instead of localhost
• Database user not assigned to the database with All Privileges

Corrupted database tables

If credentials are correct but you still get the error, a table may be corrupted. Check phpMyAdmin → select your database → look for any table showing "In use" or an error status. Repair it:

1. In phpMyAdmin, select all tables in your database
2. From the "With selected:" dropdown, choose Repair table
3. Then run Optimize table

Too many connections

If the error is intermittent (happens during high traffic), the server may be hitting MySQL connection limits. Signs:

• Error appears under load but resolves on its own
• Site works fine most of the time but crashes during traffic spikes

Solutions: enable Redis object caching (reduces database queries), upgrade your hosting plan for more resources, or move to a VPS where connection limits are higher.

After a migration

The database connection error is extremely common after migrating a site. The old host's database credentials are usually still in the config file. Update wp-config.php with the new database name, username, and password created on the new server (see How to migrate your website).

Related: Databases in cPanel | WordPress 500 error | Fixing a 500 Internal Server Error | Migrate website

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