OK, I saw another user connected successfully, and the log for his session also shows “User rich doesn’t exist”. So the real problem is with the latter three lines:
2022-07-18 08:57:21 805.163 53559 NXNODE ERROR! Application terminated too early.
2022-07-18 08:57:21 816.552 53559 NXNODE WARNING! NXClientMonitor: NXClientMonitor: NXClient –monitor could not be started. Can’t send’NX> 990 MONITOR ON type=noDesktop ‘.
2022-07-18 08:57:21 835.150 53528 NXSERVER ERROR! Received error message from node ‘localhost:4000’, ‘Session failed, application terminated prematurely.’.