When attempting to overwrite a HFS in AGOL, where the HFS is within a "Folder" in "My Content", and the folder name has a space, or a "/" in it, publishing fails, but with no error message other than failed. I don't see this restriction in the documentation. Changing the folder names will break many, many, many Python automated scripts that I have running for nightly data management. Is this documented somewhere else, in fine print? When publishing a new HFS to the same folder, the error message is more obvious "Invalid Folder". In fact, the example in Organize the content in your ArcGIS Online account—A Place to Play | ArcGIS shows a folder name with many spaces. So this is obviously a bug. With ArcMap, and Python 2.7, I am easily able to publish and overwrite content to folders with spaces or "/".