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 ('971cd782a590c44f50a469ebfd33f58c', -1, 1397981672, 1397981672, '17170289', 9, 0)

Line : 174
File : sessions.php