phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_datingforum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('50c7af0d744d8d8a93b1e62a12e41e90', -1, 1398411196, 1398411196, '36ead9f7', 19, 0)

Line : 174
File : sessions.php