on my SSH server following error message is logged: "Password change required but no TTY available". Is it possible to inform the WinSCP user about this problem during his logging attempt.
Can you provide me log file showing WinSCP trying to connect to account with expired password?
The next step is, that WinSCP offers a tty connection to the server, to change this password.
WinSCP cannot offer TTY, because neither SCP not SFTP can work with it. For non-interactive clients, SSH provides possibility to change expired password using keyboard-interactive (or similar) authentication. However I do not know how good support for this is in SSH servers.