Cannot rename "y" to "w": destination already exists
What causes it and how to fix it:
- A # or % in a file or folder name — the classic …Url APIs cannot reach it, and the old writes quietly save %25The classic …ServerRelativeUrl lookups, Files/add(url=), folders/add, moveto and copyto cannot reach it even encoded: 404/400, Exists: false for a folder that exists, and writes that answer 200 but save a literal %25; ResourcePath API with the path doubled and URL-encoded, plus its different answers on an existing target (measured)Cause and fix →