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 ('d18fef7eb42a1779efd7457b7b497002', -1, 1397913758, 1397913758, '171414c3', 10, 0)

Line : 158
File : sessions.php