I got this error from log:
2017/07/06 08:03:43 [error] 5475#0: *169482 FastCGI sent in stderr: "PHP message: PHP Fatal error: Call to undefined method models\account\mails\ResetEmail::addError() in /home/domain/public_html/wp-content/plugins/alids/includes/models/account/RecoverPassword.php on line 0" while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: www.domain.com, request: "POST /wp-admin/admin-ajax.php HTTP/2.0", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "www.domain.com", referrer: "https://www.domain.com/userlogin"
Looks like customer tried to reset email but got issue.
2017/07/06 08:03:43 [error] 5475#0: *169482 FastCGI sent in stderr: "PHP message: PHP Fatal error: Call to undefined method models\account\mails\ResetEmail::addError() in /home/domain/public_html/wp-content/plugins/alids/includes/models/account/RecoverPassword.php on line 0" while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: www.domain.com, request: "POST /wp-admin/admin-ajax.php HTTP/2.0", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "www.domain.com", referrer: "https://www.domain.com/userlogin"
Looks like customer tried to reset email but got issue.