Authenticate Subdomain

Ensure that COOKIEHASH has the same value for both, e.g.:

define( 'COOKIEHASH', md5( 'https://yourdomain.com' ) );
define( 'COOKIE_DOMAIN', '.yourdomain.com' );

See https://wordpress.stackexchange.com/a/264490/736

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)