How do I fix this 502 Bad Gateway error when setting up Django project on Ubuntu 14.04.5 box?

Everything in Unix is a file. Its arguably one of its greatest strengths. This holds true for unix domain sockets. Its why its complaining that it can't find a file.

If I look at your nginx conf…

server {
    listen 80;
    server_name mydomain.com;

    location = /favicon.ico { access_log off; log_not_found off; }
    location /static/ {
        root /home/django/FOLDER;
    }

    location / {
        include         uwsgi_params;
        uwsgi_pass      unix:/home/django/FOLDER/product_blog/product_blog.sock;
    }
}

We see you are using the uwsgi_pass directive to instruct nginx to forward requests for / to a unix domain socket. This socket is addressed by a file location.

In your uwsgi config…

[uwsgi]
project = product_blog
base = /home/django

chdir = %(base)/%(project)
home = %(base)/Env/%(project)
module = %(project).wsgi:application

master = true
processes = 2

socket = %(base)/%(project)/%(project).sock
chmod-socket = 664
vacuum = true

Through some substitution you instruct uwsgi to install a domain socket file at /home/django/product_blog/product_blog.sock. In order for nginx to connect to that socket there must be a file in the correct location with the correct privileges. When you start uwsgi it should create the *.sock file in the specified location.

things to try

1. Make sure you are using a valid file path in your uwsgi.conf(including the directories)
2. Start uwsgi and make sure your *.sock file is in the correct location
3. Make sure the proxy_pass directive in nginx is pointing to this file.