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 ('1147c19d751e6c5b1b8efd85c5ba9b1b', -1, 1550803430, 1550803430, '22e5af81', 0, 0, 0)

Line : 172
File : sessions.php