Nginx vhost prestashop on sub url - php

Question

I have 2 projects on same domain -- domain.ltd
On direct domain, i have a symfony project -- this part is OK.
But for my sake, i try to let the old prestashop site on sub url, like domain.ltd/old
So my vhost is :
# Redirect all HTTP traffic
server {
listen 80;
server_name www.domain.ltd domain.ltd;
root /home/user/projects/old.domain.ltd/;
location = /{
# On redirige toutes les requêtes vers HTTPS
rewrite ^ https://www.domain.ltd$request_uri? permanent;
}
location /old {
root /home/user/projects/old.domain.ltd/;
index index.php;
rewrite ^/old/api/?(.*)$ /webservice/dispatcher.php?url=$1 last;
rewrite ^/old/([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$1$2$3.jpg last;
rewrite ^/old/([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$1$2$3$4.jpg last;
rewrite ^/old/([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$1$2$3$4$5.jpg last;
rewrite ^/old/([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$1$2$3$4$5$6.jpg last;
rewrite ^/old/([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$1$2$3$4$5$6$7.jpg last;
rewrite ^/old/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$1$2$3$4$5$6$7$8.jpg last;
rewrite ^/old/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$7/$1$2$3$4$5$6$7$8$9.jpg last;
rewrite ^/old/([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])([0-9])(\-[_a-zA-Z0-9-]*)?(-[0-9]+)?/.+\.jpg$ /img/p/$1/$2/$3/$4/$5/$6/$7/$8/$1$2$3$4$5$6$7$8$9$10.jpg last;
rewrite ^/old/c/([0-9]+)(\-[\.*_a-zA-Z0-9-]*)(-[0-9]+)?/.+\.jpg$ /img/c/$1$2$3.jpg last;
rewrite ^/old/c/([a-zA-Z_-]+)(-[0-9]+)?/.+\.jpg$ /img/c/$1$2.jpg last;
rewrite ^/old/images_ie/?([^/]+)\.(jpe?g|png|gif)$ /js/jquery/plugins/fancybox/images/$1.$2 last;
try_files $uri $uri/ /index.php$is_args$args;
error_page 404 /old/index.php?controller=404;
location ~ ^/old/\.php$ {
try_files $uri =404;
root /home/user/projects/old.domain.ltd/;
include /etc/nginx/fastcgi_params;
fastcgi_pass unix:/var/run/php5-fpm-user.sock;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_intercept_errors on;
}
access_log /var/log/nginx/domain.ltd.old.access.log;
error_log /var/log/nginx/domain.ltd.old.error.log;
}
access_log /var/log/nginx/domain.ltd.old.access.log;
error_log /var/log/nginx/domain.ltd.old.error.log;
}
# HTTPS request on symfony
server {
listen 443 ssl;
server_name www.domain.ltd;
# this part works fine with my symfony project
}
I don't understand why my config is not working. When i go on back-office page, my web browser download the file of index.php.
If anyone have an idea ??