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 ('06e01bb56b5c2903b105eaa32c0376c3', -1, 1537443386, 1537443386, '369c33c1', -8, 0, 0)

Line : 187
File : sessions.php