White Screen of Death is a serious problem for a developer. The trouble it prepares is that It will stop you from accessing your WordPress admin panel. Its obvious to get tensed if you can't access wp-admin panel and the worst thing about white screen of death is that it sometimes only affects a specific portion of your website. Like you will only see the white screen of death on your WordPress admin but everything else keeps working alright. On the other hand, different problems may happen such as you may only see it on a specific post and as I said that everything else operates just normal.
Why this problem arises ?
May be some plugin you are using are malfunctioned or troubling, or sometimes it happens because of poor coding, maybe for just a simple white space on your function.php lead your wp-admin to go white screen of death.
You should use the WordPress debug function to see what type of errors are taking place. So add the following code in your wp-config.php file.
error_reporting(E_ALL); ini_set('display_errors', 1);
define( 'WP_DEBUG', true);
After adding this, the blank screen will now have errors, warnings, and notices. You will be able to get an idea to determine the root cause then.
One of the common error type is -
If you get an error named “Cannot modify header information - headers already sent by...”
Warning: Cannot modify header information - headers already sent by (output started at /path/to/geeklog/public_html/config.php:581) in /path/to/geeklog/public_html/system/lib-sessions.php on line 180
This is just a ‘white space’ problem so to solve just do this…
It says "output started at..." followed by a file name and a line number. That is the file (and line) that you need to edit. Ignore the second file name - that is only a file that included the file that has the whitespace. The first file is the one you have to edit, not the second one.
Other Situations -
Besides this, there may be problem with any specific plugin or It may occur because of coding problem, so uninstall plugins one by one and check if the problem is solved or not ot consider replacing the theme with another theme and then try to modify your themes coding.