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 ('b84c6d32ea8b9d46c9ae165506581aa8', -1, 1506021670, 1506021670, '36504d7c', 0, 0, 0)

Line : 187
File : sessions.php