Why do you think it's WinSCP issue? Or if it is an issue at all? It's probably just something about how the server logs the events. WinSCP cannot send "session close" after "connection close". How would it send it without having the connection opened?

Hi,
in my C#-Programm I have the following sequence:

open session (Protocol.Sftp)
put file
close session
dispose session

When I look into the log-file at the server I see

open connection
open session
put file
close session
close connection

So far, so good
BUT
sometimes I find

open connection
open session
put file
close connection
close session

Why does WinSCP send the commands sometimes in a wrong sequence?
Noone else uses the server, therefore I can be sure that there is no other session open on the server.
FTP-Log:
Nov 9 07:59:59 10.xx.xx.0 userxxx Connection from 10.xx.xx.0 port 47726 on 82.xx.xx.236 port 22
Nov 9 07:59:59 10.xx.xx.0 userxxx Accepted password for userxxx from 10.xx.xx.0 port 47726 ssh2
Nov 9 08:00:00 10.xx.xx.0 userxxx Starting session: subsystem 'sftp' for userxxx from 10.xx.xx.0 port 47726 id 0
Nov 9 08:00:00 10.xx.xx.0 userxxx session opened for local user userxxx from [10.xx.xx.0]
Nov 9 08:00:01 10.xx.xx.0 userxxx open "/ftp/incoming/TEST.DOC" flags WRITE,CREATE,TRUNCATE mode 0666
Nov 9 08:00:01 10.xx.xx.0 userxxx close "/ftp/incoming/TEST.DOC" bytes read 0 written 1211
Nov 9 08:00:01 10.xx.xx.0 userxxx [10.xx.xx.0|put|0|1211|0|0|0|2f6674702f696e636f6d696e672f5755542e444f43|]
Nov 9 08:00:01 10.xx.xx.0 userxxx set "/ftp/incoming/TEST.DOC" modtime 20201109-07:59:55
Nov 9 08:00:01 10.xx.xx.0 userxxx Connection closed by 10.xx.xx.0 port 47726
Nov 9 08:00:01 10.xx.xx.0 userxxx session closed for local user userxxx from [10.xx.xx.0]