502 bad gateway

[Maxim Dounin]

Hello!

On Wed, Dec 09, 2015 at 05:03:56PM +0100, Christ-Jan Wijtmans wrote:

> Hello,
> 
> I have a magento website working fine for months now.
> However i recently installed a PDF plugin to send invoices with emails.
> The PDF url is giving a 502 bad gateway
> "{admin}/sales_invoice/view/invoice_id/717/key/5650a40d93929f5db4383db2a169b08a/".
> I have checked around on the internet and cant find the issue here. no
> APC. increased fastcgi buffers doesnt change anything. checked nginx
> logs, magento logs and user logs but nothing.
> 
> Could anyone point me in the right direction on how to figure this one out?

If 502 is returned by nginx, this means that an error happened 
while talking to an upstream server.  Details about the error are 
expected to be available in the error log at the "error" level.  If 
you don't see error in the error log - this means that either 
logging isn't properly configured (or the error was returned by 
the upstream server, not by nginx).

Details on how to configure logging can be found here:

http://nginx.org/r/error_log

This article may be useful as well:

http://nginx.org/en/docs/debugging_log.html

-- 
Maxim Dounin
http://nginx.org/