Cannot initialize SFTP protocol. Is the host running an SFTP server?

Hi
Using Version 5.13.4 with no problems until today.
Now receive "Cannot initialize SFTP protocol. Is the host running an SFTP server?" when attempting to connect to a particular SFTP site.
Have tried on 4 PC's now and all are suddenly receiving this message.
FileZilla has no issue with connecting to this SFTP from these same PC's.
We had one PC left that could still connect to the SFTP site via WinSCP. On a hunch, we forced that PC to do the latest Windows Update and now it too can no longer connect to this SFTP site.
Logfile suggests connection is successfully made but is then terminated.

Any suggestions?
Thanks
Rick

Please attach a full session log file both from WinSCP and FileZilla (running on the same machine).

Hi

I've attached a logfile from both FileZilla and WinSCP - is this what you wee looking for?

Thanks
Rick

Thanks. Can you try setting "Preferred SFTP protocol version" to 3?
https://winscp.net/eng/docs/ui_login_sftp