PHP-FPMユーザと/var/lib/nginxのユーザを合わせてあげることで解決する。
# tail -f /var/log/nginx/www.example.net_error.log [crit] 948#0: *267 open() "/var/lib/nginx/tmp/fastcgi/6/08/0000000086" failed (13: Permission denied) while reading upstream, client: 118.xxx.yyy.126, server: 160.xxx.yyy.42, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "160.xxx.yyy.42"
# vi /etc/php-fpm.d/www.conf [www] ; Default Value: none ;prefix = /path/to/pools/$pool ;user = apache user = hogeuser ;重要 ;group = apache group = nginx (略)
# cd /var/lib
# pwd /var/lib
# ls -laht 合計 24K drwxr-xr-x 3 nginx nginx 16 7月 26 16:08 nginx (略)
バックアップ
# cp -arv nginx nginx_org
所有権変更
# chown hogeuser:nginx -R nginx
# ls -laht drwxr-xr-x 3 hogeuser nginx 16 7月 26 16:08 nginx drwxr-xr-x 3 nginx nginx 16 7月 26 16:08 nginx_org
# systemctl restart nginx # systemctl restart php-fpm
復旧。