If you do not want to post the log publicly, you can mark the attachment as private.[/size]
I am so glad you have got involved with this - I have produced a private .txt log file ( just in case I missed something ) I have replaced my windows login user names with xxx's and the internal IP addresses with xxx's but left the port number 22 visible.
So I Installed WinSCP 5.7.6 on M2
I Logged into M1 Server ( problem machine ) from M2 .. I noticed that this version of WinSCP 5.7.6 gives you no option to use stored keys ( if it does I could not find it ) .. I imported only 1 stored setting from the old WinSCP & Putty settings ... The user name and password was greyed out so I assume that WinSCP took the stored windows credentials.
I then tried to copy a file from M2 to M1 and the very same error message has appeared which I have also published but left this public, called Server M2 to M1 the log file is called M2-to-M1
Not that I pretend to know what I am looking at but I noticed in the log file this entry CYGWIN_SYSLOG.TXT ?? but I can not see that file or txt when I search for it .. could it be a hang over from my previous Cygwin install that is causing this error ? I may be talking rubbish here so pleaser dismiss it out of hand if you feel the need.
The only other thing I thought of is that there might be the remnants of an old user account on this machine that might have stored some old password ? again it might be the wrong path I am going down.
If you want me to install WinSCP 5.7.6 on the problem machine M1 and send you the log file from inside M1 I will do so - that might be the better bet please let me know