Dear martin,
I've managed to solve the problem - in Task Scheduler (Windows Server):
- Action => Edit Action => Settings
- Program/script => only the name of the BAT file
- Start in => the path to the folder with the file

Please attach a full session log file showing the problem (using the latest version of WinSCP).

Hello!

I have two virtual machines. Each of them has important data which I would like to transfer automatically by WinSCP.
- The first machine - Windows Server 2016 Datacenter + WinSCP 5.13.1
The batch file is:
open ftp://[login]:[password]@[ftp]/
lcd K:\
cd /
put [name of the folder]
exit
In Task Scheduler as arguments:
/log="C:\Program Files (x86)\WinSCP\WinSCP.log" /ini=nul /script="C:\Program Files (x86)\WinSCP\backup_transfer.bat"

- The second machine - Windows Server 2016 Datacenter + WinSCP 5.13.1
The batch file is:
open ftp://[login]:[password]@[ftp]/
lcd C:\
cd /
put [name of the folder - different than in the first machine]
exit
In Task Scheduler as arguments:
/log="C:\Program Files (x86)\WinSCP\WinSCP.log" /ini=nul /script="C:\Program Files (x86)\WinSCP\backup_transfer.bat"

As you can see - the idea is the same, but I have different results - the first machine works properly, but the second not - there is no data on FTP server after starting the task...
I would be really grateful if you could help me with this weird thing.