I wasn’t going to say anything because I haven’t used MS Windows for years. The OP wants to add a path separator at the end of a path. Why the OP wants to do that doesn’t concern me.
OTOH, as others have already mentioned, the documentation explicitly says, "If a component is an absolute path, all previous components are thrown away and joining continues from the absolute path component.” While I may not understand WHY anyone would want that to occur, this was the way it was designed; it is not a bug. The documentation also says, “The return value is the concatenation of path and any members of *paths with exactly one directory separator (os.sep) following each non-empty part except the last, meaning that the result will only end in a separator if the last part is empty.” So, the module does allow one to add a path separator at the end of the path by simply adding an empty string as the last part of the path. The following is on macOS (I don’t have a MS Windows machine): >>> import os.path >>> os.path.join('/Users/myID/a', 'b','c') '/Users/myID/a/b/c' >>> os.path.join('/Users/myID/a', 'b','c', '') '/Users/myID/a/b/c/‘ So, it does work as advertised on Python 3.8 and all the OP should need to do is add that empty string to get the OP’s desired result. Bev in TX -- https://mail.python.org/mailman/listinfo/python-list