kuchbhi.txt

upstream app_server {
  server unix:/var/www/html/config/puma.rb fail_timeout=0;
}

# Default server configuration
#
server {
        listen 80 default_server;
        listen [::]:80 default_server;

        # SSL configuration
        #
        # listen 443 ssl default_server;

        root /var/www/html;

        # Add index.php to the list if you are using PHP
#       index index.html index.htm index.nginx-debian.html;
          try_files $uri/index.html $uri @app;
        server_name _;

          location @app {
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_redirect off;

    proxy_pass http://app_server;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
  }

  error_page 500 502 503 504 /500.html;
  client_max_body_size 4G;
  keepalive_timeout 10;

  # SSL configuration goes here if needed
}
this is nginx configuration file and we got error 502 bad request can tell me why