Můj Easy Redmine ukazuje 502 Bad Gateway.
There are many possible causes of this error. Here are a few tips:
- browser cache problem - try deleting cache from the browser
 - dns problem
 - server setting problem
 
First check your connection and network (verify that server is reachable by using a ping command or traceroute command). Firewall server side.
If all above seems fine, try to get some information from nginx error.logs. Check nginx error.log at the server side - /var/log/nginx/error.log
Double check that your nginx configuration matches the standard. Standard nginx configuration can be found here:
https://www.redmine.org/projects/redmine/wiki/HowTo_configure_Nginx_to_run_Redmine
Example of an nginx configuration (as is used by Easy Software). It's quite similar to official one only few variables are optimized:
user www-data;
 worker_processes  8;
worker_rlimit_nofile 60000;
error_log  /var/log/nginx/error.log;
 pid        /var/run/nginx.pid;
events {
     worker_connections  10240;
     # multi_accept on;
 }
http {
     ssl_protocols  TLSv1 TLSv1.1 TLSv1.2;  # dont use SSLv3 ref: POODLE
     include       /etc/nginx/mime.types;
                 default_type  application/octet-stream;
                 server_names_hash_bucket_size 2048;
access_log /var/log/nginx/access.log;
    sendfile        on;
     #tcp_nopush     on;
    #keepalive_timeout  0;
     keepalive_timeout  65;
     tcp_nodelay        on;
     send_timeout 1800;
     client_body_timeout  1800;
     client_header_timeout 1800;
     proxy_read_timeout 1800;
     client_max_body_size 220m;
     fastcgi_buffer_size 64K;
     fastcgi_buffers 128 16k;
     proxy_max_temp_file_size 0;
     types_hash_max_size 4096;
     types_hash_bucket_size 128;
    proxy_busy_buffers_size   256k;
     proxy_buffers 8 256k;
     proxy_buffer_size 256k;
     gzip  on;
     gzip_disable "MSIE [1-6]\.(?!.*SV1)";
    include /etc/nginx/conf.d/*.conf;
     include /etc/nginx/sites-enabled/*;
     include /etc/nginx/sites-auto/*;
 }
Other possible causes of 502 error include...
Unicorn is not running at all, due to
- Insufficient permissions
 - Wrong version of passenger
 - Wrong Ruby version
 - Missing gems
 - Broken filesystem
 
To find out the exact problem, you need to check error logs in unicorn or apache + application log from Easy Redmine (log/production.log)
Timeout
Pokud je nastaven nízký timeout, tato chyba se objeví při:
- velkých exportech
 - přetížení serveru
 - spouštění rake úloh z GUI
 
Limit připojení k MySQL
Ujistěte se, že máte dostatečný počet povolených připojení k MySQL. Záleží to na počtu uživatelů, ale měli byste mít povoleno alespoň 100 připojení.
