AMFPHP gameway.php 502 Error

Question

I am developing an app that is built with Flex and AMFPHP. Everything works fine, however, in some cases such as if I'm calling the same function in 5 seconds intervals, or when I call 2 different functions in short periods, I get a fault saying

RPC Fault faultString="error" faultCode="Channel.Call.Failed" faultDetail="NetConnection.Call.Failed: HTTP: Status 502

And at nginx error.log, I receive

recv() failed (104: Connection reset by peer) while reading response header from upstream, .... 
request: "POST /amfphp/gateway.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: 

Using nginx, php5-fpm.

How can I solve this? Thanks in advance.

Answer 1

Looks like some error (not exception) appeared in PHP code execution. To see the real server answer (usually - this is HTML text with error description) you can use any traffic debugger (i use FireBug, or Opera Dragonfly, or Service Capture, or Charles)