WinSCP does not do any virus checks nor does it ever "quarantine" any files.
It must be your system that does it.
If you want us to check further, please post session log file. But I'm not sure if that brings anything.

Hi

I've been using WinSCP for years now and while using it today it all of a sudden wouldn't upload a text file saying

System Error. Code: 225.
Operation did not complete successfully because the file contains a virus or potentially unwanted software

It has been uploading the file all morning and it only contains text. I scanned the file and no virus was found. I installed the latest version, but the same problem. I disabled all of my firewalls and antivirus, but it still won't upload it and quarantines it somewhere, I don't know where. Sorry if this is a dumb question, but any help would be appreciated. Thanks.