Enable Error Logging in php-fpm
Edit your pool file
vi /etc/php/7.0/fpm/pool.d/www.conf
Add
catch_workers_output = yes php_flag[display_errors] = on php_admin_value[error_log] = /var/log/fpm-php.www.log php_admin_flag[log_errors] = on
if you only enable “log_errors”, then errors go to default nginx error log.