Fatal error: Call to undefined method Mage_Adminhtml_Block_Widget::getrowurl()

If you getting blank pages or fatal errors on MANAGE CATEGORIES page, then here is the solution :

Go To app/code/core/Mage/Adminhtml/Block/Widget/Grid.php

Search function getRowUrl in the file.

public function getRowUrl($item)
{
$res = parent::getRowUrl($item);
return ($res ? $res : '#');
}

Replace this function with below function:

public function getRowUrl($row) 
{ 
return $this->getUrl('*/*/edit', array('instance_id' => $row->getId())); 
}