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 ('cfdf1234025024ba446dd6dc3e1da6a0', -1, 1548198608, 1548198608, '22e0663c', 0, 0, 0)

Line : 172
File : sessions.php