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 ('c764d35e79d345a45dbbe1d06d1b5933', -1, 1548247064, 1548247064, '3457fdca', 1, 0, 0)

Line : 187
File : sessions.php