You possibly do not have create permissions to the folder. So WinSCP fails to create a temporary file for the transfer.
You have two options:
-
Grant write permissions to the folder to the user or group you log in with (
myuser), or change the ownership of the folder to the user, or -
Disable a transfer to temporary file.
In Preferences, go to Transfer > Endurance page and in Enable transfer resume/transfer to temporary file name for select Disable:
