After reading the documentation here to rename an item, I'm not sure why I am getting a “not found” (409).
Here is the data of the item provided by https://api.dropboxapi.com/2/files/list_folder
Screenshot of the list_folder API response

Interesting that “id:” is prefixed in the string. As expected, I do get a 400 response because it does not match '[-_0-9a-zA-Z]+'
Going back to the requirements detailed in the docs, I took “id:” out to become “a_nxjuJ9zcUAAAAAAAAACQ”.
Screenshot of the request

I get back this 409 response.

I also tried removing “id:a” to “_nxjuJ9zcUAAAAAAAAACQ”, and when that didn't work, I removed “id:a_” and it still responded it couldn't be found. I thought perhaps because it's a folder, that's why, but even a PNG file could not be found/renamed either.