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 ('15c0a8ab1037a269bf8b99627e0bfda0', -1, 1534873786, 1534873786, '36c42a08', 9, 0, 0)

Line : 187
File : sessions.php