Magento: An Error occured while saving the URL rewrite

1

            try {
                $this->_getWriteAdapter()->insert($this->getMainTable(), $rewriteData);
            }
            catch (Exception $e) {
                Mage::throwException(Mage::helper('catalog')->__('An error occurred while saving the URL rewrite.'));
            }

2

            try {
                $this->_getWriteAdapter()->insert($this->getMainTable(), $rewriteData);
            }
            catch (Exception $e) {
                //Mage::throwException(Mage::helper('catalog')->__('An error occurred while saving the URL rewrite.'));
            }