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 ('a55a6347eccedebfd6d5f7833e730d3d', -1, 1398073082, 1398073082, '36cc86b7', 9, 0)

Line : 174
File : sessions.php