This issue has been added to the tracker:
https://winscp.net/tracker/1701

I just wanted to mention this problem so that it could be addressed in later versions.

The only ways to address is that either:
– Microsoft fixes the bug introduced in Windows 10 1803
– I implement some configuration option that will allow a drop to a configured set of network drives. – Would you be interested in testing this option?

Thanks for the quick reply.

Currently I use temporary folders as workaround. And thats ok.
I just wanted to mention this problem so that it could be addressed in later versions.

Would be nice if the shell extension would even work with 1803 (or later versions) some day.

Many thanks.

Yes, it's related to a bug in Windows 10 1803. On this version of Windows 10, the drag & drop shell extension actually does not work at all.
https://winscp.net/tracker/1644

Also documented here:
https://winscp.net/eng/docs/ui_pref_dragdrop#fake_file

Do you have a fixed/limited set of network drives, where you drag files to? If so, I can implement some configuration option that will allow drop to configured set of network drives.

Dragging a file from WinSCP's Explorer view to a network folder in Windows Explorer (e.g. to \\a\b) does not work when using the shell extension in Windows 10 1803 (64 bit).
An error message is displayed and the file wont be copied.

Drag & drop works fine for local files.

The problem with the network folders seems to be related to Windows 10 1803 as it works on Windows 7.

Sorry for not providing a detailed log ... I'm currently working on Windows 7.

Im using WinSCP version 5.13.3.

Thanks for this really good application and your support.