Troubleshooting PHP-FPM and Nginx: 502 Bad Gateway Issue on Ubuntu / Debian / Mint

Solving PHP-FPM and NGINX: 502 Bad Gateway Error on Linux

The Step-by-step Troubleshooting shows you How to Solve the PHP-FPM and NGINX: 502 Bad Gateway Issue on Linux Ubuntu/Debian-based Systems.

Usually this Misbehavior is due to an Improper Ownership of the NGINX Server…

1. Give the Right Permissions to NGINX.

   sudo usermod -a -G www-data nginx

2. Set to Listen FastCgi on 127.0.0.1:9000.

   cat /etc
   ginx/conf.d/default.conf

   Confronts with:

   server {
   listen 80 default_server;
   listen [::]:80 default_server;
   
   root /var/www/html;/nindex index.php index.html index.htm;
   
   server_name YOURIPADDRESS;
   
   # pass the PHP scripts to FastCGI server at /var/run/php5-fpm.sock
   location ~ ^/index\.php(/|$) {
   fastcgi_pass 127.0.0.1:9000;
   fastcgi_split_path_info ^(.+\.php)(/.*)$;/ninclude fastcgi_params;
   fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
   fastcgi_param  HTTPS              off;
   }
   
   }
   

   And then:

   cat /etc/apache2/conf-available/php5-fpm.conf

   Setting the Host parameter as below:

   
   AddHandler php5.fcgi .php
   Action php5.fcgi /php5.fcgi
   Alias /php5.fcgi /usr/lib/cgi-bin/php5.fcgi
   FastCgiExternalServer /usr/lib/cgi-bin/php5.fcgi -host 127.0.0.1:9000 -pass-header Authorization -idle-timeout 3600
   
   Require all granted
   
     
   

3. Finally, Restart php5-fpm & nginx Services.

   sudo service php5-fpm restart && sudo service nginx restart