Opencart gives error 502 or 504, how to fix?

Question

PHP

I make a trial order, go to the control panel, click (show order), the panel takes a long time to load and then gives an error 502 or 504 time gateway, what could be the reason for this ??
nginx 1.8
php 5.6.9
debian 8

Answer 1

This is not issued by opencart, but by nginx.
You have too little timeout for rnr.
Write the following line in php.ini
max_execution_time 150;
If it doesn't help, share the nginx log (the default directory is /var/log/nginx/error.log

Answer 2

also, only nginx hangs longer.
on apache, it works without problems.