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 ('21ee121cb780aee1034ba2fea8e2446d', -1, 1537301638, 1537301638, '36a6cb11', 58, 0, 0)

Line : 187
File : sessions.php