An Error has occurred

exception 'Am_Exception_InputError' with message 'Invalid product id specified [0]' in /home/cibercom/public_html/application/cart/controllers/IndexController.php:87
Stack trace:
#0 /home/cibercom/public_html/library/Am/Mvc/Controller.php(128): Cart_IndexController->productAction()
#1 /home/cibercom/public_html/library/Am/Mvc/Controller.php(105): Am_Mvc_Controller->_runAction('productAction')
#2 /home/cibercom/public_html/library/Zend/Controller/Dispatcher/Standard.php(307): Am_Mvc_Controller->dispatch('productAction')
#3 /home/cibercom/public_html/library/Zend/Controller/Front.php(956): Zend_Controller_Dispatcher_Standard->dispatch(Object(Am_Mvc_Request), Object(Am_Mvc_Response))
#4 /home/cibercom/public_html/library/Am/App.php(2268): Zend_Controller_Front->dispatch()
#5 /home/cibercom/public_html/index.php(92): Am_App->run()
#6 {main}:Invalid product id specified [0]