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 ('c1342c51d1c1a7a051f1ecc5a2f7eb5a', -1, 1406549973, 1406549973, '1716b3d2', 19, 0)

Line : 174
File : sessions.php