I received a phone call from a customer who said a coupon code was not working. I then proceeded to Shopping Cart Price Rules in my Admin and the whole site crashed with an exception error. The report in log says the following
a:5:{i:0;s:23:"Unsupported data type N";i:1;s:1398:"#0 /home/and21159/public_html/lib/Unserialize/Reader/Arr.php(102): Unserialize_Reader_ArrValue->read('N', ';')
#1 /home/and21159/public_html/lib/Unserialize/Parser.php(53): Unserialize_Reader_Arr->read('N', ';')
#2 /home/and21159/public_html/app/code/core/Mage/Core/Helper/UnserializeArray.php(44): Unserialize_Parser->unserialize('a:7:{s:4:"type"...')
#3 /home/and21159/public_html/app/code/core/Mage/Rule/Model/Abstract.php(179): Mage_Core_Helper_UnserializeArray->unserialize('a:7:{s:4:"type"...')
#4 /home/and21159/public_html/app/code/core/Mage/Adminhtml/controllers/Promo/QuoteController.php(92): Mage_Rule_Model_Abstract->getConditions()
#5 /home/and21159/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Adminhtml_Promo_QuoteController->editAction()
#6 /home/and21159/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('edit')
#7 /home/and21159/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#8 /home/and21159/public_html/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch()
#9 /home/and21159/public_html/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#10 /home/and21159/public_html/index.php(83): Mage::run('', 'store')
#11 {main}";s:3:"url";s:76:"/index.php/admin/promo_quote/edit/id/2/key/4943fbaea25dba236be939e69b17ad3c/";s:11:"script_name";s:10:"/index.php";s:4:"skin";s:5:"admin";}
How do I fix this?