If you have WordPress Multisite Error Establishing Database Connection on your WordPress website, it is a fatal error.
This WordPress error occurs when WordPress is failed to make a DB connection to the database.
1st check :
`DB_NAME, DB_USER, DB_PASSWORD, B_HOST`
& each site’s .htaccess entries if it defines any site name statically..
2nd check : `wp_config file –
define('MULTISITE', true);`
define('COOKIE_DOMAIN', $_SERVER['HTTP_HOST'] );
Once u set this multisite config, you must reload your site & login once to wp-admin..
3rd check : WP_DB tables >>
'wp_blogs' >> 'path' to "/"`
'wp_site’ >> 'path' to "/"
(dont mention any real path here, so it will take it dynamically)