How to show errors when you get a white screen in EE. Turning up the debugging will reveal PHP errors.

0-Debugging-ExpressionEngine.md

Overview

Below are two techniques to help debug the WSOD (white screen of death), usually a 500 server error, in an ExpressionEngine site. The Basic-Debugging option will be suitable in most cases and is specific to ExpressionEngine. The Advanced-Debugging is generic and applicable to any PHP based software. If the basic debugging does not work, try the advanced.

If you get a WSOD you will need to first get your site to reveal an error before reporting it to EllisLab or the add-on developer. Simply reporting "I get a white screen" does not give the developer enough information to assist you. An error message on the other hand will point the developer to the source of the issue.

1-Basic-Debugging.txt

In your config.php file, find $config['debug'] and set it to 2:

  $config['debug'] = 2;

In your index.php and admin.php files, find $debug and set it to 1:

  $debug = 1;

2-Advanced-Debugging.txt

<?php

// Taken from http://stackoverflow.com/questions/1475297/phps-white-screen-of-death/18208549#18208549

// Add this to the top of your index.php file.

ini_set('display_errors', 'On');
ini_set('html_errors', 0);
error_reporting(-1);

function ShutdownHandler() {
    if(@is_array($error = @error_get_last())) {
        return(@call_user_func_array('ErrorHandler', $error));
    };

    return(TRUE);
};

register_shutdown_function('ShutdownHandler');

function ErrorHandler($type, $message, $file, $line) {
    $_ERRORS = Array(
        0x0001 => 'E_ERROR',
        0x0002 => 'E_WARNING',
        0x0004 => 'E_PARSE',
        0x0008 => 'E_NOTICE',
        0x0010 => 'E_CORE_ERROR',
        0x0020 => 'E_CORE_WARNING',
        0x0040 => 'E_COMPILE_ERROR',
        0x0080 => 'E_COMPILE_WARNING',
        0x0100 => 'E_USER_ERROR',
        0x0200 => 'E_USER_WARNING',
        0x0400 => 'E_USER_NOTICE',
        0x0800 => 'E_STRICT',
        0x1000 => 'E_RECOVERABLE_ERROR',
        0x2000 => 'E_DEPRECATED',
        0x4000 => 'E_USER_DEPRECATED'
    );

    if(!@is_string($name = @array_search($type, @array_flip($_ERRORS)))) {
        $name = 'E_UNKNOWN';
    };

    return(print(@sprintf("%s Error in file %s at line %d: %s\n", $name, @basename($file), $line, $message)));
};

$old_error_handler = set_error_handler("ErrorHandler");
?>

its also worth noting that near the bottom of index.php and admin.php is the following:

if (DEBUG == 1)
{
    error_reporting(E_ALL);
    @ini_set('display_errors', 1);
}
else
{
    error_reporting(0); 
}

Change it to this and it sometimes helps reveal errors:

// if (DEBUG == 1)
// {
    error_reporting(E_ALL);
    @ini_set('display_errors', 1);
// }
// else
// {
//  error_reporting(0); 
// }

Expression engine was supressing a mysql error which was really annoy...hadn't installed the PHP mysql extension and also had the wrong host address.

	function db_connect()
	{
		if ($this->port != '')
		{
			$this->hostname .= ':'.$this->port;
		}

		return @mysql_connect($this->hostname, $this->username, $this->password, TRUE);
	}