I am currently running CMS5 R2, and I have "Allow advanced upload of files using for example drag-and-drop" enabled. I have no problems with uploading files that do not currently exist in the file manager. I have a problem with I try to upload an existing file that I want to overwrite. It gives me a  error and I'm not sure how to resolve. This problem only happens when I use the drag and drop feature. If I try to drag an existing file, I get this error. However, if I click the "Add new file" icon, then browse for a file it will upload and overwrite the existing file with no problems.
This can be a pain when trying to overwrite multiple files and I would just like to drag multiple files into the file manager and have them upload and overwrite existing files. Is anyone else gettting this error?
After quickly checking this in the same version I do not have any trouble with dragging and dropping multiple files that already exist. I get the check question whether I want to replace the files and then they are replaced.
Let me investigate this further and get back to you.