You will get this error if your website is not able to reach the database. This could either be due to a password authentication issue or the MySQL host might be down. What can you do? 

 

Open the wp-config file from the File Manager in cPanel. 

 

The portion you are looking for is this, 

 

/** MySQL database username */ 

define('DB_USER', 'username_here'); 

/** MySQL database password */ 

define('DB_PASSWORD', 'password_here'); 

/** MySQL hostname */ 

define('DB_HOST', 'localhost'); 

 

These details much match those you have in cPanel under the MySQL section. Reset the database username and password. On our cPanel servers your host is always ‘localhost’.