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 ('60e8bead4ed74b0494f9823f6449da9b', -1, 1553544300, 1553544300, '22e42a19', 18, 0, 0)

Line : 187
File : sessions.php