nginx error connect to php5-fpm.sock failed (13: Permission denied)

Question

I update nginx to 1.4.7 and php to 5.5.12, After that I got the 502 error. Before I update everything works fine.

Answer 1

I just got this error again today as I updated my machine (with updates for PHP) running Ubuntu 14.04. The distribution config file /etc/php5/fpm/pool.d/www.conf is fine and doesn't require any changes currently.

I found the following errors:

dmesg | grep php
[...]
[ 4996.801789] traps: php5-fpm[23231] general protection ip:6c60d1 sp:7fff3f8c68f0 error:0 in php5-fpm[400000+800000]
[ 6788.335355] traps: php5-fpm[9069] general protection ip:6c5d81 sp:7fff98dd9a00 error:0 in php5-fpm[400000+7ff000]

The strange thing was that I have 2 sites running that utilize PHP-FPM on this machine one was running fine and the other (a Tiny Tiny RSS installation) gave me a 502, where both have been running fine before.

I compared both configuration files and found that fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; was missing for the affected site.

Both configuration files now contain the following block and are running fine again:

location ~ \.php$ {
        fastcgi_pass unix:/var/run/php5-fpm.sock;
        include /etc/nginx/snippets/fastcgi-php.conf;
}

Update

It should be noted that Ubuntu ships two fastcgi related parameter files and also a configuration snippet which is available since Vivid and also in the PPA version. The solution was updated accordingly.

Diff of the fastcgi parameter files:

$ diff -up fastcgi_params fastcgi.conf
--- fastcgi_params      2015-07-22 01:42:39.000000000 +0200
+++ fastcgi.conf        2015-07-22 01:42:39.000000000 +0200
@@ -1,4 +1,5 @@

+fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
 fastcgi_param  QUERY_STRING       $query_string;
 fastcgi_param  REQUEST_METHOD     $request_method;
 fastcgi_param  CONTENT_TYPE       $content_type;

Configuration snippet in /etc/nginx/snippets/fastcgi-php.conf

# regex to split $uri to $fastcgi_script_name and $fastcgi_path
fastcgi_split_path_info ^(.+\.php)(/.+)$;

# Check that the PHP script exists before passing it
try_files $fastcgi_script_name =404;

# Bypass the fact that try_files resets $fastcgi_path_info
# see: http://trac.nginx.org/nginx/ticket/321
set $path_info $fastcgi_path_info;
fastcgi_param PATH_INFO $path_info;

fastcgi_index index.php;
include fastcgi.conf;