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, session_admin) VALUES ('e070f90d1e9c8ec056f45aefcd05d530', -1, 1425312925, 1425312925, '36a61870', 16, 0, 0)

Line : 187
File : sessions.php