phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('3c7ea7f57f1df706effc196ea01621b9', -1, 1413927053, 1413927053, '3213ce31', 33, 0)

Line : 315
File : sessions.php