502 Bad Gateway when saving settings in subscription

[MislavO]

Hello.

I had random bad gateways and other NGINX errors, but I've fixed that already with settings in nginx conf/plesk php.ini. for example I have set :

apc.enabled = 0

in:
# /usr/local/psa/admin/conf/php.ini
(phpmyadmin workaround)

In nginx.conf I have:

proxy_connect_timeout 600;
proxy_send_timeout 600;
proxy_read_timeout 600;
send_timeout 600;

proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;

and:
# grep buffer /etc/sw-cp-server/config
fastcgi_buffers 32 32k;
fastcgi_buffer_size 64k;


After that being said, I've noticed that now when, for example, I enter subscription (basically any subscription) and change hosting Plan or customize settings, all websites on the server break for 1-2sec showing 502 Bad Gateway and then after refresh they work again.

Nginx error log - exactly that moment when it broke showed:

# tail -50 /var/log/nginx/error.log | grep "http://demo.DOMAIN.COM/URL"

2013/12/16 08:07:01 [error] 34201#0: *4875535 connect() failed (111: Connection refused) while connecting to upstream, client: <IP>, server: demo.DOMAIN.COM, request: "GET /URL/js/Double/Up/Right/6.png HTTP/1.1", upstream: "http://<IP>:7080/URL/js/Double/Up/Right/6.png", host: "demo.DOMAIN.COM", referrer: "http://demo.DOMAIN.COM/URL"

There are also random errors like:

2013/12/16 08:07:02 [error] 34201#0: *4925146 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: <IP>, server: demo.DOMAIN.COM, request: "GET /URL/jqueryeasy/jquerynoconflict.js HTTP/1.1", upstream: "http://<IP>:7080/URL/jqueryeasy/jquerynoconflict.js", host: "demo.DOMAIN.COM", referrer: "http://demo.DOMAIN.COM/URL"

Using Plesk 11.5, Debian 7 and apache+nginx (fastcgi, there is no php-fpm support).

Note:
Can't find this on my server:
http://kb.parallels.com/en/118671 (and /tmp/mysql.sock does not exist, how to procceed with this one if it's important with current problem)

Websites are working and loading normal apart from that.