El plugin WP Debugging debe tener un archivo wp-config.phpque sea escribible por el sistema de archivos.

Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/wp-content/plugins/wp-debugging/src/Bootstrap.php:77) in /var/www/html/wp-includes/pluggable.php on line 1298 Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/wp-content/plugins/wp-debugging/src/Bootstrap.php:77) in /var/www/html/wp-includes/pluggable.php on line 1301