phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a614fb41d46ad1d833203a049077934c', -1, 1417237280, 1417237280, '365a42ed', -4, 0, 0)

Line : 187
File : sessions.php