nginx 500错误，而不是404

我有以下nginxconfiguration（在/etc/nginx/sites-available/default ）

 server { listen 80; ## listen for ipv4; this line is default and implied listen [::]:80 default ipv6only=on; ## listen for ipv6 root /usr/share/nginx/www; index index.php index.html index.htm; server_name _; location / { try_files $uri $uri/ /index.html; } error_page 404 /404.html; location ~ \.php$ { try_files $uri =404; fastcgi_split_path_info ^(.+\.php)(/.+)$; fastcgi_pass unix:/tmp/php5-fpm.sock; fastcgi_index index.php; include fastcgi_params; } location ~ /\.ht { deny all; } } 

而不是一个404错误，我得到了500个服务器错误在破碎的url。 我怎样才能纠正这一点？

    位置 / {
             try_files $ uri $ uri / = 404;
     }