USR2 signal not work, failed to upgrade executable

[q1548]

Hello,

Both nginx_new and nginx_old are good, after USR2 signal be sent to the
master process, it can not start new master process. I use these steps:

1. cp -f nginx_new nginx_old
2. kill -USR2 $( cat /usr/local/nginx/logs/nginx.pid )
3. ps aux | grep nginx
no new master process, only old master process, error.log show:

[emerg] 19205#0: bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
[emerg] 19205#0: still could not bind()
nginx: [emerg] still could not bind()

Please help, thanks.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,287439,287439#msg-287439