Magento white screen of death - php

Question

I am trying to compile my magento store's code. Initially compiling was producing an error which I tracked down to the Fooman Speedster advanced module. I removed the module entirely from my store's code and again recompiled. The compilation successfully completed this time and all classes (around 7500) could be seen in the/includes/src/ folder.
However after compilation, my site's frontend is showing the white screen of death with no error being generated in the apache error log. What is strange is that the backend is working perfectly fine.
I have also increased my memeory limit for php scripts to 1024M so that php running out of memory is not the problem.
Any suggestions as to what might be the propblem or how to go about tracking the problem/bug.

Answer 1

Reposting my answer from here. Hope it will help
Magento white screen on Admin log in page?
I faced with the same problem. Actually it was even worse because it was a commercial product and a new hosting for me with really strange server configuration. So I couldn't made errors appear in any log file.
As I've found out the magento white screen means some PHP Fatal error occured. So there is a proper way to show them. Just add at the begin of your index.php
ini_set('error_reporting', E_ERROR);
register_shutdown_function("fatal_handler");
function fatal_handler() {
$error = error_get_last();
echo("<pre>");
print_r($error);
}
And you will see what is really happening with your magento.

Answer 2

This is how I got it corrected(Hope will help you guys):
Use the following code in your index.php file
ini_set('error_reporting', E_ERROR);
register_shutdown_function("fatal_handler");
function fatal_handler() {
$error = error_get_last();
echo("<pre>");
print_r($error);
}
In my case it tolde me that error/503.php was unavailable.
3.The issue was with testimonial extension I used(http://www.magentocommerce.com/magento-connect/magebuzz-free-testimonial.html)
I deleted the testimonial.xml file in my app/etc/modules/testimoanial.xml.
delete “maintenance.flag" file.

Answer 3

I deleted all the folders from my var->cache directory and frontend started working.

Answer 4

As I read, it is caused by when your Persistent Shopping Cart enabled.
Set System > Configuration > Persistent Shopping Cart > General Options > Enable Persistence to disabled and try again.
You can have a look here.

Answer 5

It's a common problem with compilation, you can temporarily disable compilation by editing /includes/config.php and commenting out these lines:
define('COMPILER_INCLUDE_PATH', dirname(__FILE__).DIRECTORY_SEPARATOR.'src');
define('COMPILER_COLLECT_PATH', dirname(__FILE__).DIRECTORY_SEPARATOR.'stat');

Answer 6

After a lot of research and testing, I have come to the conclusion that while compiling there may be several errors that lead to the white screen of death. These will not be visible for some reason leaving you with no clue as to where is the problem.
In most cases - custom modules or installed modules are the culprits. The only reliable way to debug the magento compilation is to use the xdebug.scream = 1 in the xdebug configuration. This will scream out the error file/reason which can then be worked upon.
A better explanation could be found here:
http://www.brimllc.com/2012/03/magento-fun-with-debugging-the-magento-compiler/

Answer 7

Another reason for not seeing any error in any log might be the APC cache.
See my Stackoverflow answer here for more details.
You can
disable it via .htaccess: php_flag apc.cache_by_default off
clear the apc cache every time the page is called: add at the top of index.php apc_clear_cache(); (no solution but good to see if the APC is the problem)