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 ('12b9764174b2077a63aff6e130724675', -1, 1397853792, 1397853792, '36cc4098', 0, 0)

Line : 158
File : sessions.php