Magento 1.9.3.1 - Error 500 on products in cart if updated in admin

Question

I'm running Magento 1.9.3.1 and I'm having a very weird issue I never encountered having multiple Magento websites.

If I add a product to cart then update it in back office, I have an error 500 on frontend on all pages. I have to delete browser history to get the pages back.

Any idea on what could be causing this ? Could it be a Magento bug ?

Logs are giving :

mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 130968 bytes) in app/code/core/Mage/Sales/Model/Resource/Quote/Item/Option/Collection.php on line 101 on home page

mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 2245 bytes) in app/code/local/Mage/Eav/Model/Entity/Collection/Abstract.php on line 1138 on category page

mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 98 bytes) in lib/Zend/Db/Statement/Pdo.php on line 291 on product page

mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 256 bytes) in lib/Varien/Simplexml/Element.php on line 195 on cart page

I'm on a dedicated server running multiple Magento stores OK.

Answer 1

There may be chances that If you are using any 3rd Party extensions you will face these kind of errors , disable those extensions in app/etc/modules folder & try....