Error: session has already been started by session.auto-start or session_start()

#0 /home/vhosts/guideistanbul.net/http/library/Zend/Session/Namespace.php(143): Zend_Session::start(true)
#1 /home/vhosts/guideistanbul.net/http/library/Zend/Auth/Storage/Session.php(87): Zend_Session_Namespace->__construct('Zend_Auth')
#2 /home/vhosts/guideistanbul.net/http/application/modules/default/controllers/DefaultController.php(33): Zend_Auth_Storage_Session->__construct('Zend_Auth')
#3 /home/vhosts/guideistanbul.net/http/library/Zend/Controller/Dispatcher/Standard.php(268): Default_Controller_Action->__construct(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http), Array)
#4 /home/vhosts/guideistanbul.net/http/library/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#5 /home/vhosts/guideistanbul.net/http/library/Zend/Application/Bootstrap/Bootstrap.php(97): Zend_Controller_Front->dispatch()
#6 /home/vhosts/guideistanbul.net/http/library/Zend/Application.php(366): Zend_Application_Bootstrap_Bootstrap->run()
#7 /home/vhosts/guideistanbul.net/http/index.php(34): Zend_Application->run()
#8 {main}