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 ('601d7f48cc2f3760d1e08e62353e2e7f', -1, 1537585393, 1537585393, '36c63452', -2, 0, 0)

Line : 189
File : sessions.php