phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a35edb802b39b2a08b2f2eba4609eb38', -1, 1548112494, 1548112494, '3457fdca', -8, 0, 0)

Line : 172
File : sessions.php