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 ('700d879eadb6a4d18f9578991a3edcc4', -1, 1398355639, 1398355639, '365385bd', 9, 0)

Line : 174
File : sessions.php