yep same issue here on 1.7.7.4
Not exactly the same issue but it happens when I want to disconnect
PHP Fatal error: Uncaught Error: Call to a member function getId() on null in /prestashop/classes/Cookie.php:548
Stack trace:
#0 /prestashop/classes/Cookie.php(501): CookieCore->getSession('110')
#1 /prestashop/classes/Cookie.php(265): CookieCore->deleteSession()
#2 /prestashop/classes/Customer.php(1240): CookieCore->mylogout()
#3 /prestashop/classes/controller/FrontController.php(364): CustomerCore->mylogout()
#4 /prestashop/classes/controller/Controller.php(287): FrontControllerCore->init()
#5 /prestashop/classes/Dispatcher.php(518): ControllerCore->run()
#6 /prestashop/index.php(28): DispatcherCore->dispatch()
#7 {main}
thrown in /prestashop/classes/Cookie.php on line 548
are you all using" login as customer" or a cache module or not? thanks?