phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO sw_forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('f6f798eda2536713ede1a2a363d220ad', -1, 1413956229, 1413956229, '365144b9', 47, 0, 0)

Line : 187
File : sessions.php