I almost give up what is wrong. I've setup web server by using nginx. But I can't send user mail on WordPress. When I create user or reset password, WordPress must stop.
The environment is bellow.
Ubuntu0.16.04.1
Nginx 1.12.1
PHP 7.0.1
FPM/FastCGI
postfix 3.1.0
(I can send mail by 'mail' command.)
WordPress 4.4.2
Nginx Erro log is bellow----
PHP message: PHP Fatal error: require_once(): Failed opening required '/var/www/html/cms/wp-includes/class-phpmailer.php' (include_path='.:/usr/share/php') in /var/www/html/cms/wp-includes/pluggable.php on line 275" while reading response header from upstream, client: {global_ip}, server: {domain}, request: "POST /cms/wp-admin/user-edit.php HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.0-fpm.sock:", host: "{host_name}", referrer: "/cms/wp-admin/user-edit.php?user_id=2&wp_http_referer=%2Fcms%2Fwp-admin%2Fusers.php"
Any help or hint?