Weird privilege errors on Ubuntu 20.04

[Palvelin Postmaster]

I wonder what can cause these weird error log entries? The log entries indicate a PID which doesn’t exist. Does nginx launch some temporary process when it starts?

Nginx 1.21.0 on Ubuntu 20.04.

root at k2:~# systemctl restart nginx

root at k2:~# tail /var/log/nginx/error.log
2021/06/08 21:25:32 [warn] 1287733#1287733: the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /etc/nginx/nginx.conf:21
2021/06/08 21:25:32 [emerg] 1287733#1287733: cannot load certificate key "/etc/ssl/private/nginx-selfsigned.key": BIO_new_file() failed (SSL: error:0200100D:system library:fopen:Permission denied:fopen('/etc/ssl/private/nginx-selfsigned.key','r') error:2006D002:BIO routines:BIO_new_file:system lib)

root at k2:~# ls -lh /etc/ssl/private/ |grep selfsigned
-rw-r----- 1 root ssl-cert 1.7K Jul  8 17:12 nginx-selfsigned.key

root at k2:~# cat /etc/nginx/nginx.conf |grep ^user
user www-data;

root at k2:~# ps -auxw |grep nginx
root     1287600  0.0  0.0  56148  6504 ?        Ss   21:25   0:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
www-data 1287601  0.7  0.1  58544 15652 ?        S    21:25   0:05 nginx: worker process
www-data 1287602  0.0  0.1  57556 13696 ?        S    21:25   0:00 nginx: worker process
www-data 1287603  0.0  0.1  56392  9184 ?        S    21:25   0:00 nginx: cache manager process