phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('82d6769e68370d4b708b5568ba9c66c3', -1, 1534602180, 1534602180, '36c660c6', 4, 0, 0)

Line : 172
File : sessions.php