This means your site cannot reach its database. Work through these:
- Check credentials: confirm the database name, user, password, and host in your config (WordPress
wp-config.phpor.env) match what is in cPanel's MySQL Databases. Host should belocalhost. - Re-check the user: ensure the user is added to the database with ALL PRIVILEGES.
- Reset the password in cPanel and update your config to match.
- Repair the database via phpMyAdmin if it may be corrupted.
If credentials are correct and it still fails, the MySQL service may be overloaded or down. Open a ticket and we will check the server right away.