phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('7a0bc8dae096631e5440c96369e0d44d', -1, 1417241093, 1417241093, '36ea07a1', 14, 0, 0)

Line : 187
File : sessions.php