nginx GET HTTP/1.1" 500 5

Question

What's the problem?

I access the page without problems but when I try to access a link with jQuery, error 500 appears

195.16.143.6 - XXXXX [09/Aug/2016:08:54:12 +0000] "GET /XXXX.php HTTP/1.1" 500 5 " http://XXXXXX/ " "Mozilla/5.0 (X11; Fedora; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36"

My conf:

server {
            ## Escucha en el puerto 80 (HTTP)
            listen 80;

            ## Raíz donde se encuentra la página Web
            root /srv/www/arbol/;

            ## Orden de prioridad de los archivos index
            index index.php index.html index.htm;

            server_name arbol.bichomen.com;
            access_log /var/log/nginx/arbol.log;

            try_files $uri $uri/ =404;
            auth_basic "Restricted";
            auth_basic_user_file /etc/nginx/.htpasswd;

            location / {
                    ## try_files $uri $uri/ =404;
            }

            location ~ \.php$ {
                   root /srv/www/arbol;
                   try_files $uri =404;
                   fastcgi_split_path_info ^(.+\.php)(/.+)$;
                   fastcgi_pass unix:/var/run/php5-fpm/arbol.sock;
                   fastcgi_param PATH_TRANSLATED $document_root$fastcgi_script_name;
                   fastcgi_index index.php;
                  ##  fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                   include fastcgi_params;
            }
    }

Answer 1

I found the error, it is a problem with PHP, and I generated another question:

Call to undefined function