Hi i have upgraded my site from J1.5 to the newest via jupgrade... But after that i have problem with my K2 component. On frontend i have blank page with error message

Use of undefined constant K2_CB - assumed 'K2_CB'
Fatal error: Call to a member function userProfileUrl() on a non-object in D:\xampp\htdocs\lochneska\jupgrade\components\com_k2\helpers\route.php on line 45

Really dont know where is problem, i didn´t use Community builder or any additional plugins