Apache error 500 after PHP upgrade

When upgrading your server from old PHP release to 5.4 make sure your application does not use deprecated functions such as session_register.
This function may be used in older CMS versions, as Tiger CMS.

To comment out all occurrences of incompatible functions in the code you can use following command:
Example for session_register:

find . -type f -exec sed -i 's/session_register/\/\/session_register/g' {} \;

Generic troubleshooting steps for error 500 in Apache:

1. Check Apache error log
/var/log/apache2/error.log

2. Turn on PHP Error reporting in etc/php.ini (/etc/php5/apache2/php.ini)

error_reporting(E_ALL);

3. Create an info.php file to test php, with content:

<?php phpinfo; ?>

So you can see what version you use and if it is loaded correctly.

Good Luck!

Nginx + SSL + PHP-FPM sample config

server {
    listen       443;
    server_name  server.name.com;
    root   /d1/html/phpbb;

    ssl                  on;
    ssl_certificate /etc/ssl/certificate.crt;
    ssl_certificate_key /etc/ssl/private.key;

    ssl_session_timeout  5m;

    ssl_protocols  SSLv2 SSLv3 TLSv1;
    ssl_ciphers  HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers   on;

    location / {
        index index.php index.html index.htm;
    }

    location ~ \.php$ {
        include         /etc/nginx/fastcgi_params;
        if (-f $request_filename) {
        fastcgi_pass   127.0.0.1:9000;
        }
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
    }
}