Magento Error Processing Request

2016-03-27T12:02:55+00:00 ERR (3):
exception 'Exception' with message 'Warning: get_class() expects parameter 1 to be object, boolean given  in /home/{sitename}/public_html/app/code/core/Mage/Core/Model/App.php on line 1340' in /home/{sitename}/public_html/app/code/core/Mage/Core/functions.php:245
Stack trace:
#0 [internal function]: mageCoreErrorHandler(2, 'get_class() exp...', '/home/{sitename}/...', 1340, Array)
#1 /home/{sitename}/public_html/app/code/core/Mage/Core/Model/App.php(1340): get_class(false)
#2 /home/{sitename}/public_html/app/code/core/Mage/Core/Model/App.php(1317): Mage_Core_Model_App->_callObserverMethod(false, '', Object(Varien_Event_Observer))
#3 /home/{sitename}/public_html/app/Mage.php(448): Mage_Core_Model_App->dispatchEvent('checkout_type_o...', Array)
#4 /home/{sitename}/public_html/app/code/core/Mage/Sales/Model/Service/Quote.php(186): Mage::dispatchEvent('checkout_type_o...', Array)
#5 /home/{sitename}/public_html/app/code/core/Mage/Sales/Model/Service/Quote.php(249): Mage_Sales_Model_Service_Quote->submitOrder()
#6 /home/{sitename}/public_html/app/code/core/Mage/Checkout/Model/Type/Onepage.php(785): Mage_Sales_Model_Service_Quote->submitAll()
#7 /home/{sitename}/public_html/app/code/core/Mage/Checkout/controllers/OnepageController.php(579): Mage_Checkout_Model_Type_Onepage->saveOrder()
#8 /home/{sitename}/public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Checkout_OnepageController->saveOrderAction()
#9 /home/{sitename}/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('saveOrder')
#10 /home/{sitename}/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))
#11 /home/{sitename}/public_html/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#12 /home/{sitename}/public_html/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#13 /home/{sitename}/public_html/index.php(87): Mage::run('', 'store')
#14 {main}