SSL connection failed: session reuse required

Server asks for authentication with a client certificate.
Disconnected from server
Could not retrieve directory listing
SSL connection failed: session reuse required

Thanks for the log.

Please post a new session log files on Debug 2 log level both from 5.17 and the earlier version that was working for you.

this is the current log 5.17. the previous version i do not have logs for. i tried installing it after and produced the same result.

5.15.9 portable works fine

I have the exact same problem with the exact same error messages.
Reverted to a previous version (5.19.9) and everything works fine now.

Limiting TLS to version 1.2 should make it working in WinSCP 5.17 too.
https://winscp.net/eng/docs/ui_login_tls

This issue has been added to the tracker:
https://winscp.net/tracker/1831