phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO start_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('c8406d8e6fca36bcee3d33a48fed0f2a', -1, 1418915934, 1418915934, '36a35908', -1, 0)

Line : 158
File : sessions.php