I have added this issue to the tracker:
https://winscp.net/tracker/1977
https://winscp.net/tracker/1977
Before posting, please read how to report bug or request support effectively.
Bug reports without an attached log file are usually useless.
. 2021-04-06 05:02:58.815 Command-line: "\\***\bin\WinSCP.exe" /console=5.17.10 /consoleinstance=_2744_951 "/log=WinSCP-put-log.txt" "/loglevel=-1" "/command" "open sftp://***:***@***.com:10022" "cd /In" "put -nopreservetime -nopermissions forward_E406017.txt" "exit"
. 2021-04-06 05:03:04.971 --------------------------------------------------------------------------
. 2021-04-06 05:03:04.971 Using SFTP protocol.
. 2021-04-06 05:03:04.986 Doing startup conversation with host.
. 2021-04-06 05:03:05.111 SFTP version 3 negotiated.
. 2021-04-06 05:03:05.111 We believe the server has signed timestamps bug
. 2021-04-06 05:03:05.111 We will use UTF-8 strings until server sends an invalid UTF-8 string as with SFTP version 3 and older UTF-8 strings are not mandatory
. 2021-04-06 05:03:05.111 Getting current directory name.
. 2021-04-06 05:03:05.236 Startup conversation with host finished.
< 2021-04-06 05:03:05.236 Script: Active session: [1] ***@***.com
> 2021-04-06 05:03:05.236 Script: cd /In
. 2021-04-06 05:03:05.236 Cached directory change via "/In" to "/In".
. 2021-04-06 05:03:05.236 Getting current directory name.
< 2021-04-06 05:03:05.236 Script: /In
> 2021-04-06 05:03:05.236 Script: put -nopreservetime -nopermissions forward_E406017.txt
< 2021-04-06 05:03:05.252 Script: Using configured transfer settings different from factory defaults.
. 2021-04-06 05:03:05.252 Copying 1 files/directories to remote directory "/In" - total size: 662
. 2021-04-06 05:03:05.252 File: 'forward_E406017.txt' [2021-04-06T09:02:54.033Z] [662]
. 2021-04-06 05:03:05.252 Copying "forward_E406017.txt" to remote directory started.
. 2021-04-06 05:03:05.565 Transfer done: 'forward_E406017.txt' => '/In/forward_E406017.txt' [633]
. 2021-04-06 05:03:05.565 Copying finished: Transferred: 633, Elapsed: 0:00:00, CPS: 0/s
> 2021-04-06 05:03:05.565 Script: exit
. 2021-04-06 05:03:05.565 Script: Exit code: 0
. 2021-04-06 05:03:05.565 Closing connection.
. 2021-04-06 05:03:05.690 Remote side unexpectedly closed network connection
< 2021-04-06 05:03:05.690 Script: Remote side unexpectedly closed network connection