phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'd9ddd73699c134599eb70634b6ecd847' for key 1

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('d9ddd73699c134599eb70634b6ecd847', -1, 1409158468, 1409158468, '36c4da71', 3, 0, 0)

Line : 187
File : sessions.php