phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '0' 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 ('dafad02c3e1b24c5d2a34ae57ba02308', -1, 1550606821, 1550606821, '22e473d8', -4, 0, 0)

Line : 187
File : sessions.php