My Easy Redmine hiển thị 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

If low timeout is configured, this error will appear on:

• large exports
• overload of server
• rake tasks run from the GUI

Limit of MySQL connections

Make sure you have a sufficient number of connections allowed to MySQL. It depends on the number of users, but you should have at least a 100 allowed.