Function wp_set_wpdb_vars sets the database table prefix and the format specifiers for database table columns. Is this a multisite wordpress installation?
Check file permissions for those files to see if that’s the issue for your blank site.
Hi it looks like an issue with your database, maybe caused by a recent upgrade of your wp installation, try to use define( ‘WP_ALLOW_REPAIR’, true ); in your wp-config.php and then access {$your_site}/wp-admin/maint/repair.php to see if that fix the problem.
