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 ('fd33aeac82742e8d78c587ff00d9e12e', -1, 1417241509, 1417241509, '36ea07a1', -9, 0, 0)

Line : 187
File : sessions.php