phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a7a34b8674fdf7e68ae1b6f41b356fc5', -1, 1506430042, 1506430042, '369c5d3c', -4, 0, 0)

Line : 187
File : sessions.php