When i add to cart any product it is going to blank page.

When i add to cart any product it is going to blank page. And then complete magento site got blank any idea ??

Hi,

Can you please share the URL of your web site.

Regards
Pulkit Seth
http://www.pulkitseth.com

Go to System->Configuration

Then Enabled the log setting under Advanced->Developer->Log Setting

Then save product and then see the system.log file into

/var/www/html/magento/var/log

May help you

For enable error reporting

In Index page change the following:

error_reporting(E_ALL | E_STRICT);
to

error_reporting(E_ALL);
Set $_SERVER['MAGE_IS_DEVELOPER_MODE'] = true

and uncomment this line #ini_set('display_errors', 1);

In Errors folder rename "local.xml.sample" to local.xml.

hope this help.

Don't forget to set full access permissions (777) to the following folder: /var/log, since that is the place where those log files are stored.
UPDATE-1

to solve the issue please use the following steps: Clean Magento cache, either using Flush Cache at System -> Configuration -> Cache Magement in Magento Backend or using Clean Cache button at Store settings in your Managing panel.

Disable Magento Compiler at the System -> Tools -> Compilation screen One by one, disable recently installed modules at System -> Configuration > Advanced -> Advanced -> Disable Modules output and flush Magento cache after each operation.