I saw your more detailed post at Server Fault:
How to make HTTP OPTIONS responses working for WebDAV with Apache2?

WinSCP does not really require the OPTIONS request support. But when it receives "Unauthorized" response, it assumes that the credentials are incorrect. If you make your server respond anything else, it would work.

I have a problem using WinSCP for WebDAV with an Apache2 webserver that offers WebDAV via mod_dav. I have tried other WebDAV clients, they work fine. So what is this? I looked deeper into the communication and saw that other clients start WebDAV connection with an HTTP PROPFIND request, but WinSCP wants the connection with an HTTP OPTIONS request, and (for whatever reason) this does not work with Apache2, I never saw it working, or I am missing information on how to configure this on the Apache2 side. Apache2 gives an error (e.g. 401 or 403) and WinSCP then does not connect, but the error box appears.

The HTTP OPTIONS request is optional, as other WebDAV clients prove, you can get by very well without it. So my question here is, can I configure WinSCP to skip the HTTP OPTIONS request (or ignore it if it gives an error) so that I can then use it for WebDAV with Apache2 module mod_dav? Alternatively, does anyone here know how to make Apache2 answer HTTP OPTIONS requests correctly, what configuration did you test the WebDAV against when developing it? Has anyone ever managed to get WinSCP to successfully do a WebDAV (for uploads) with Apache2 mod_dav?