Indeed, a hint might show. But I do not really think this is a common problem.

Even though that fixed it, this really looks like a problem that should have some sort of fix applied. I can understand why nothing may be done. But, literally, one can say it broke drag and drop or transfer.

It could be detected and put up a warning even. Something like, user tried to drag and drop but nothing really happened, so provide helpful hint. Something like that should in theory work.

Indeed, the file is excluded by the default file mask.
So I believe this problem should be resolved now:
Can't revert Synchonize UI include mask to default behavior

I created a session log where I created a local file, test_local.c, and tried to move it to the remote server with no luck. I then created a remote file, test_remote.c, which was successfully created on the remote server with some dummy content. Neither file could be dragged to the other server.

I did notice that my broken mask (the one that I can't delete) from my other thread appeared in the log; I have a feeling that solving that problem will solve this problem as well.

Please post session log file that shows how you cannot first upload a file to the server directly, yet immediately afterwards you can upload the same contents from the editor.

Anonymous wrote:

Creating a file which will be empty 0 bytes, and sending bytes are two different things. When something goes wrong, that can leave a 0 byte file around if no cleanup is done by the code.

I agree 100%. What I should have said is that I was able to create a file on the remote server by right-clicking on the remote panel and selecting "New", edit it with the built-in text editor and add content, and then save it. The new file, complete with all of my edits, was now sitting on the remote server. Yet I cannot drag and drop it back across to my local server. It acts just like it has completed successfully with no error popups, but 0 kB are transferred and no local file is present, not even an empty one.

The exact same thing happens if I create a file locally and try dragging and dropping it from the local server to the remote server.

Creating a file which will be empty 0 bytes, and sending bytes are two different things. When something goes wrong, that can leave a 0 byte file around if no cleanup is done by the code.

I'm just a guest. See what Martin says. It will most likely either be logs, or known issue.

Although I have been using WinSCP successfully with this particular site for several years, earlier today suddenly all files transfer "successfully" with 0 kB transferred. This is true both ways. However, I can create a file directly on the remote server by right-clicking in the remote window and selecting "New". I can edit files directly in the remote window and delete files in the remote window. I just can't drag files back and forth anymore, even after restarting the application and even restarting the machine.

I can also use a different local machine and connect to the same server with the same credentials using WinSCP and transfer files successfully via drag and drop, so I don't think it has anything to do with the remote server.

I don't see how to bring up a status window to see if there are any failure codes being issued by the server, or what the difference is between dragging and dropping a file vs. creating a new file on the remote server.