php logs are not displayed

[npf]

nginx does not show php error logs.

according to
http://serverfault.com/questions/417102/nginx-not-logging-php-errors

setting catch_workers_output = true in /etc/php5/fpm/pool.d/www.conf
could solve the issue, but I just get 502 Bad Gateway

Also, can you recall in what using nginx is better than apache for oardocker ?

[npf]

Also, before changing anything, the following errors up in nginx error.log

root@frontend /var/log/nginx
$ cat error.log 
2016/02/07 20:29:49 [notice] 181#181: using inherited sockets from "3:4;"
2016/02/07 20:29:49 [crit] 181#181: getsockname() of the inherited socket #4 failed (88: Socket  operation on non-socket)
2016/02/07 20:29:49 [alert] 181#181: close() built-in log failed (9: Bad file descriptor)
nginx: [alert] close() built-in log failed (9: Bad file descriptor)

[npf]

Ooops, looks like there was no error to show.
There's something bizarre in the code which does not output errors...

[npf]

Nevermind, I had a javascript error, which did not show up in nginx logs of course.

Before closing this issue, explanation about /var/log/nginx would be welcome however, as well a why nginx is better than apache.