"502 Bad Gateway" on first request in a setup with Apache 2.4-servers as upstreams

[hheiko]

I don't think there is an OS relation on the frontend, the same problem
occurs with an Centos Nginx as Reverse proxy in front of 3 Apache backends
on Centos - but it never occurs on windows based Apache backends...

But we´re on version 1.11.4.1 Lion (http://nginx-win.ecsds.eu)

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,268306,269511#msg-269511