Deleting product gives 500 fatal error

Question

I'm running Magento 1.9.3.3 and whenever I try to delete a product I get an HTTP ERROR 500 page. Everything else seems to work normally.

The error log says:

PHP Fatal error: Call to a member function joinRel() on boolean in /home/xxxxxxxx/public_html/app/code/core/Mage/Tag/Model/Tag.php on line 127

This is the relevant section from that tag.php file:

    protected function _getProductEventTagsCollection(Varien_Event_Observer $observer)
{
    return $this->getResourceCollection()
                    ->joinRel()
                    ->addProductFilter($observer->getEvent()->getProduct()->getId())
                    ->addTagGroup()
                    ->load();
}

I can't find any reference to this online at all and I'm completely stumped. Has anyone got any ideas, or suggest a fix?

Many thanks.

Answer 1

Apparently $this->getResourceCollection() returns false.

If you look at the code in app/code/core/Mage/Core/Model/Abstract.php, you can see that it tries to load a resource collection for a specified _resourceCollectionName:

public function getResourceCollection()
    {
        if (empty($this->_resourceCollectionName)) {
            Mage::throwException(Mage::helper('core')->__('Model collection resource name is not defined.'));
        }
        return Mage::getResourceModel($this->_resourceCollectionName, $this->_getResource());
    }

Did you see anything in the error logs? Is the Exception thrown for example (/var/log/exception.log by default)? Look like Magento tries to load a resource Collection model that is somehow not defined.